This is difference between the default preference of Firefox 46.0 and one of 45.0.2.

Preference difference
PrefFirefox 45.0.2Firefox 46.0
alerts.showFaviconsundefinedfalse
apz.displayport_expiry_msundefined15000
apz.num_paint_duration_samples3undefined
apz.use_paint_durationtrueundefined
apz.x_skate_size_multiplier2.51.25
apz.x_stationary_size_multiplier3.01.5
browser.apps.URLhttps://marketplace.firefox.com/discovery/undefined
browser.meta_refresh_when_inactive.disabledundefinedfalse
browser.newtabpage.remote.modeundefinedproduction
browser.panorama.animate_zoomtrueundefined
browser.pocket.apiapi.getpocket.comundefined
browser.pocket.enabledtrueundefined
browser.pocket.enabledLocalescs de en-GB en-US en-ZA es-ES es-MX fr hu it ja ja-JP-mac ko nl pl pt-BR pt-PT ru zh-CN zh-TWundefined
browser.pocket.oAuthConsumerKey40249-e88c401e1b1f2242d9e441c4undefined
browser.pocket.sitegetpocket.comundefined
browser.pocket.useLocaleListtrueundefined
browser.safebrowsing.appRepURLhttps://sb-ssl.google.com/safebrowsing/clientreport/download?key=%GOOGLE_API_KEY%undefined
browser.safebrowsing.blockedURIs.enabledundefinedfalse
browser.safebrowsing.downloads.remote.block_dangerousundefinedtrue
browser.safebrowsing.downloads.remote.block_dangerous_hostundefinedtrue
browser.safebrowsing.downloads.remote.block_potentially_unwantedundefinedfalse
browser.safebrowsing.downloads.remote.block_uncommonundefinedfalse
datareporting.healthreport.currentDaySubmissionFailureCount0undefined
datareporting.healthreport.documentServerNamespacemetricsundefined
datareporting.healthreport.documentServerURIhttps://fhr.data.mozilla.com/undefined
datareporting.healthreport.lastDataSubmissionFailureTime0undefined
datareporting.healthreport.lastDataSubmissionRequestedTime0undefined
datareporting.healthreport.lastDataSubmissionSuccessfulTime0undefined
datareporting.healthreport.logging.consoleEnabledtrueundefined
datareporting.healthreport.logging.consoleLevelWarnundefined
datareporting.healthreport.logging.dumpEnabledfalseundefined
datareporting.healthreport.logging.dumpLevelDebugundefined
datareporting.healthreport.nextDataSubmissionTime0undefined
datareporting.healthreport.pendingDeleteRemoteDatafalseundefined
datareporting.healthreport.service.enabledtrueundefined
datareporting.healthreport.service.loadDelayFirstRunMsec60000undefined
datareporting.healthreport.service.loadDelayMsec10000undefined
datareporting.healthreport.service.providerCategorieshealthreport-js-provider-defaultundefined
datareporting.policy.dataSubmissionEnabled.v2falseundefined
datareporting.policy.firstRunTime0undefined
devtools.command-button-noautohide.enabledundefinedfalse
devtools.loader.hotreloadundefinedfalse
devtools.markup.collapseAttributesundefinedtrue
devtools.memory.custom-census-displaysundefined{}
devtools.memory.custom-dominator-tree-displaysundefined{}
devtools.performance.ui.show-jit-optimizationsundefinedfalse
devtools.responsive.html.enabledundefinedfalse
devtools.scratchpad.enabledundefinedfalse
devtools.webconsole.autoMultilineundefinedtrue
dom.abortablepromise.enabledfalseundefined
dom.details_element.enabledundefinedfalse
dom.document.scrollingElement.enabledundefinedfalse
dom.ipc.cpows.forbid-unsafe-from-browserundefinedtrue
dom.mozBrowserFramesEnabledundefinedtrue
dom.permissions.enabledfalsetrue
dom.vr.add-test-devices10
dom.vr.poseprediction.enabledundefinedfalse
gfx.logging.peak-texture-usage.enabledundefinedfalse
gfx.logging.texture-usage.enabledundefinedfalse
identity.fxaccounts.remote.force_auth.urihttps://accounts.firefox.com/force_auth?service=sync&context=fx_desktop_v2https://accounts.firefox.com/force_auth?service=sync&context=fx_desktop_v3
identity.fxaccounts.remote.signin.urihttps://accounts.firefox.com/signin?service=sync&context=fx_desktop_v2https://accounts.firefox.com/signin?service=sync&context=fx_desktop_v3
identity.fxaccounts.remote.signup.urihttps://accounts.firefox.com/signup?service=sync&context=fx_desktop_v2https://accounts.firefox.com/signup?service=sync&context=fx_desktop_v3
intl.ime.use_simple_context_on_password_fieldtruefalse
javascript.options.dump_stack_on_debuggee_would_runundefinedfalse
javascript.options.throw_on_debuggee_would_runundefinedfalse
javascript.options.wasmundefinedfalse
layers.async-pan-zoom.enabledfalsetrue
layout.accessiblecaret.allow_script_change_updatesundefinedfalse
layout.accessiblecaret.always_tiltundefinedfalse
layout.accessiblecaret.caret_shown_when_long_tapping_on_empty_contentundefinedfalse
layout.css.text-align-unsafe-value.enabledundefinedfalse
layout.css.text-emphasis.enabledfalsetrue
media.benchmark.framesundefined300
media.benchmark.timeoutundefined1000
media.benchmark.vp9.thresholdundefined150
media.format-reader.webmtrueundefined
media.getusermedia.screensharing.allowed_domainswebex.com,*.webex.com,ciscospark.com,*.ciscospark.com,projectsquared.com,*.projectsquared.com,*.room.co,room.co,beta.talky.io,talky.io,*.clearslide.com,appear.in,*.appear.in,tokbox.com,*.tokbox.com,*.sso.francetelecom.fr,*.si.francetelecom.fr,*.sso.infra.ftgroup,*.multimedia-conference.orange-business.com,*.espacecollaboration.orange-business.com,free.gotomeeting.com,g2m.me,*.g2m.me,example.com,*.mypurecloud.com,*.mypurecloud.com.au,spreed.me,*.spreed.me,*.spreed.com,air.mozilla.org,*.circuit.com,*.yourcircuit.com,circuit.siemens.com,yourcircuit.siemens.com,circuitsandbox.net,*.unify.com,tandi.circuitsandbox.netwebex.com,*.webex.com,ciscospark.com,*.ciscospark.com,projectsquared.com,*.projectsquared.com,*.room.co,room.co,beta.talky.io,talky.io,*.clearslide.com,appear.in,*.appear.in,tokbox.com,*.tokbox.com,*.sso.francetelecom.fr,*.si.francetelecom.fr,*.sso.infra.ftgroup,*.multimedia-conference.orange-business.com,*.espacecollaboration.orange-business.com,free.gotomeeting.com,g2m.me,*.g2m.me,example.com,*.mypurecloud.com,*.mypurecloud.com.au,spreed.me,*.spreed.me,*.spreed.com,air.mozilla.org,*.circuit.com,*.yourcircuit.com,circuit.siemens.com,yourcircuit.siemens.com,circuitsandbox.net,*.unify.com,tandi.circuitsandbox.net,*.ericsson.net,*.cct.ericsson.net,*.opentok.com,*.conf.meetecho.com,meet.jit.si,*.meet.jit.si,web.stage.speakeasyapp.net,web.speakeasyapp.net,*.hipchat.me,*.beta-wspbx.com,*.wspbx.com,*.unifiedcloudit.com,*.smartboxuc.com,*.smartbox-uc.com,*.panterranetworks.com,pexipdemo.com,*.pexipdemo.com,pex.me,*.pex.me,*.rd.pexip.com,1click.io,*.1click.io,*.fuze.com,*.fuzemeeting.com,*.thinkingphones.com,gotomeeting.com,*.gotomeeting.com,gotowebinar.com,*.gotowebinar.com,gototraining.com,*.gototraining.com,citrix.com,*.citrix.com,expertcity.com,*.expertcity.com,citrixonline.com,*.citrixonline.com,g2m.me,*.g2m.me,gotomeet.me,*.gotomeet.me,gotomeet.at,*.gotomeet.at
media.gstreamer.enable-blacklisttrueundefined
media.gstreamer.enabledtrueundefined
media.hardware-video-decoding.force-enabledundefinedfalse
media.peerconnection.video.max_bitrate20000
media.peerconnection.video.min_bitrate2000
media.peerconnection.video.start_bitrate3000
media.wave.decoder.enabledundefinedtrue
narrate.enabledundefinedtrue
narrate.rateundefined0
narrate.testundefinedfalse
narrate.voiceundefinedautomatic
network.mdns.use_js_fallbackundefinedfalse
network.notify.changedfalsetrue
security.ssl3.ecdhe_ecdsa_chacha20_poly1305_sha256undefinedtrue
security.ssl3.ecdhe_rsa_chacha20_poly1305_sha256undefinedtrue
security.view-source.reachable-from-inner-protocolundefinedfalse
security.webauth.u2fundefinedfalse
security.webauth.u2f.softtokenundefinedfalse
security.webauth.u2f.usbtokenundefinedfalse
selectioncaret.enabledfalseundefined
selectioncaret.inflatesize.threshold40undefined
services.kinto.baseundefinedhttps://firefox.settings.services.mozilla.com/v1
services.kinto.bucketundefinedblocklists
services.kinto.onecrl.checkedundefined0
services.kinto.onecrl.collectionundefinedcertificates
services.sync.prefs.sync.services.sync.syncedTabs.showRemoteIconsundefinedtrue
services.sync.syncedTabs.showRemoteIconsundefinedtrue
touchcaret.enabledfalseundefined
touchcaret.expiration.time3000undefined
touchcaret.inflatesize.threshold40undefined
ui.popup.disable_autohideundefinedfalse
urlclassifier.blockedTableundefinedtest-block-simple,mozplugin-block-digest256
app.support.e10sAccessibilityUrlundefinedhttps://support.mozilla.org/1/firefox/%VERSION%/%OS%/%LOCALE%/accessibility-ppt
apz.allow_immediate_handoffundefinedtrue
apz.num_paint_duration_samples3undefined
apz.paint_skipping.enabledundefinedtrue
apz.record_checkerboardingundefinedfalse
apz.use_paint_durationtrueundefined
apz.x_skate_size_multiplier2.51.25
apz.x_stationary_size_multiplier3.01.5
browser.apps.URLhttps://marketplace.firefox.com/discovery/undefined
browser.laterrun.enabledundefinedfalse
browser.newtabpage.remoteundefinedfalse
browser.panorama.animate_zoomtrueundefined
browser.pocket.apiapi.getpocket.comundefined
browser.pocket.enabledtrueundefined
browser.pocket.enabledLocalescs de en-GB en-US en-ZA es-ES es-MX fr hu it ja ja-JP-mac ko nl pl pt-BR pt-PT ru zh-CN zh-TWundefined
browser.pocket.oAuthConsumerKey40249-e88c401e1b1f2242d9e441c4undefined
browser.pocket.sitegetpocket.comundefined
browser.pocket.useLocaleListtrueundefined
browser.safebrowsing.appRepURLhttps://sb-ssl.google.com/safebrowsing/clientreport/download?key=%GOOGLE_API_KEY%undefined
browser.safebrowsing.downloads.remote.urlundefinedhttps://sb-ssl.google.com/safebrowsing/clientreport/download?key=%GOOGLE_API_KEY%
browser.uitour.surveyDurationundefined7200
datareporting.healthreport.currentDaySubmissionFailureCount0undefined
datareporting.healthreport.documentServerNamespacemetricsundefined
datareporting.healthreport.documentServerURIhttps://fhr.data.mozilla.com/undefined
datareporting.healthreport.lastDataSubmissionFailureTime0undefined
datareporting.healthreport.lastDataSubmissionRequestedTime0undefined
datareporting.healthreport.lastDataSubmissionSuccessfulTime0undefined
datareporting.healthreport.logging.consoleEnabledtrueundefined
datareporting.healthreport.logging.consoleLevelWarnundefined
datareporting.healthreport.logging.dumpEnabledfalseundefined
datareporting.healthreport.logging.dumpLevelDebugundefined
datareporting.healthreport.nextDataSubmissionTime0undefined
datareporting.healthreport.pendingDeleteRemoteDatafalseundefined
datareporting.healthreport.service.enabledtrueundefined
datareporting.healthreport.service.loadDelayFirstRunMsec60000undefined
datareporting.healthreport.service.loadDelayMsec10000undefined
datareporting.healthreport.service.providerCategorieshealthreport-js-provider-defaultundefined
datareporting.policy.dataSubmissionEnabled.v2falseundefined
datareporting.policy.firstRunTime0undefined
devtools.memory.custom-dominator-tree-breakdownsundefined{}
dom.abortablepromise.enabledfalseundefined
dom.input.fallbackUploadDirundefined
dom.permissions.enabledfalsetrue
dom.vr.add-test-devices10
extensions.e10sBlocksEnablingundefinedtrue
extensions.pocket.enabledundefinedtrue
full-screen-api.transition.timeoutundefined500
general.smoothScroll.currentVelocityWeightingundefined0.25
general.smoothScroll.stopDecelerationWeightingundefined0.4
gfx.content.use-native-pushlayerundefinedtrue
gfx.downloadable_fonts.fallback_delay_shortundefined100
identity.fxaccounts.remote.force_auth.urihttps://accounts.firefox.com/force_auth?service=sync&context=fx_desktop_v2https://accounts.firefox.com/force_auth?service=sync&context=fx_desktop_v3
identity.fxaccounts.remote.signin.urihttps://accounts.firefox.com/signin?service=sync&context=fx_desktop_v2https://accounts.firefox.com/signin?service=sync&context=fx_desktop_v3
identity.fxaccounts.remote.signup.urihttps://accounts.firefox.com/signup?service=sync&context=fx_desktop_v2https://accounts.firefox.com/signup?service=sync&context=fx_desktop_v3
intl.ime.use_simple_context_on_password_fieldtruefalse
javascript.options.shared_memoryundefinedfalse
layers.async-pan-zoom.enabledfalsetrue
layers.single-tile.enabledundefinedtrue
layout.accessiblecaret.bar.enabledundefinedtrue
layout.css.font-display.enabledundefinedfalse
layout.css.prefixes.device-pixel-ratio-webkitundefinedfalse
layout.css.text-emphasis.enabledfalsetrue
media.ffvpx.enabledundefinedtrue
media.format-reader.webmtrueundefined
media.getusermedia.screensharing.allowed_domainswebex.com,*.webex.com,ciscospark.com,*.ciscospark.com,projectsquared.com,*.projectsquared.com,*.room.co,room.co,beta.talky.io,talky.io,*.clearslide.com,appear.in,*.appear.in,tokbox.com,*.tokbox.com,*.sso.francetelecom.fr,*.si.francetelecom.fr,*.sso.infra.ftgroup,*.multimedia-conference.orange-business.com,*.espacecollaboration.orange-business.com,free.gotomeeting.com,g2m.me,*.g2m.me,example.com,*.mypurecloud.com,*.mypurecloud.com.au,spreed.me,*.spreed.me,*.spreed.com,air.mozilla.org,*.circuit.com,*.yourcircuit.com,circuit.siemens.com,yourcircuit.siemens.com,circuitsandbox.net,*.unify.com,tandi.circuitsandbox.netwebex.com,*.webex.com,ciscospark.com,*.ciscospark.com,projectsquared.com,*.projectsquared.com,*.room.co,room.co,beta.talky.io,talky.io,*.clearslide.com,appear.in,*.appear.in,tokbox.com,*.tokbox.com,*.sso.francetelecom.fr,*.si.francetelecom.fr,*.sso.infra.ftgroup,*.multimedia-conference.orange-business.com,*.espacecollaboration.orange-business.com,free.gotomeeting.com,g2m.me,*.g2m.me,example.com,*.mypurecloud.com,*.mypurecloud.com.au,spreed.me,*.spreed.me,*.spreed.com,air.mozilla.org,*.circuit.com,*.yourcircuit.com,circuit.siemens.com,yourcircuit.siemens.com,circuitsandbox.net,*.unify.com,tandi.circuitsandbox.net,*.ericsson.net,*.cct.ericsson.net,*.opentok.com,*.conf.meetecho.com,meet.jit.si,*.meet.jit.si,web.stage.speakeasyapp.net,web.speakeasyapp.net,*.hipchat.me,*.beta-wspbx.com,*.wspbx.com,*.unifiedcloudit.com,*.smartboxuc.com,*.smartbox-uc.com,*.panterranetworks.com,pexipdemo.com,*.pexipdemo.com,pex.me,*.pex.me,*.rd.pexip.com,1click.io,*.1click.io,*.fuze.com,*.fuzemeeting.com,*.thinkingphones.com,gotomeeting.com,*.gotomeeting.com,gotowebinar.com,*.gotowebinar.com,gototraining.com,*.gototraining.com,citrix.com,*.citrix.com,expertcity.com,*.expertcity.com,citrixonline.com,*.citrixonline.com,g2m.me,*.g2m.me,gotomeet.me,*.gotomeet.me,gotomeet.at,*.gotomeet.at
media.gstreamer.enable-blacklisttrueundefined
media.gstreamer.enabledtrueundefined
media.navigator.audio.full_duplexundefinedfalse
media.peerconnection.simulcastundefinedtrue
media.peerconnection.video.max_bitrate20000
media.peerconnection.video.min_bitrate2000
media.peerconnection.video.min_bitrate_estimateundefined0
media.peerconnection.video.start_bitrate3000
network.http.request.max-attemptsundefined6
network.notify.changedfalsetrue
network.sts.max_time_for_pr_close_during_shutdownundefined5000
plugins.rewrite_youtube_embedsundefinedfalse
print.print_via_parentundefinedfalse
privacy.trackingprotection.ui.enabledundefinedfalse
selectioncaret.enabledfalseundefined
selectioncaret.inflatesize.threshold40undefined
touchcaret.enabledfalseundefined
touchcaret.expiration.time3000undefined
touchcaret.inflatesize.threshold40undefined
webextensions.testsundefinedfalse
Default pref Javascript files
FileFirefox 45.0.2Firefox 46.0
browser/omni.ja!/defaults/preferences/devtools.jspresentpresent
browser/omni.ja!/defaults/preferences/firefox-branding.jspresentpresent
browser/omni.ja!/defaults/preferences/firefox-l10n.jspresentpresent
browser/omni.ja!/defaults/preferences/firefox.jspresentpresent
browser/omni.ja!/defaults/preferences/webide-prefs.jspresentpresent
omni.ja!/defaults/pref/services-sync.jspresentpresent
omni.ja!/greprefs.jspresentpresent
webapprt/omni.ja!/defaults/preferences/prefs.jspresentpresent