This is difference between the default preference of Firefox 48.0 beta 5 and one of 47.0.1.

Preference difference
PrefFirefox 47.0.1Firefox 48.0 beta 5
app.update.urlhttps://aus5.mozilla.org/update/3/%PRODUCT%/%VERSION%/%BUILD_ID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/update.xmlhttps://aus5.mozilla.org/update/6/%PRODUCT%/%VERSION%/%BUILD_ID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%SYSTEM_CAPABILITIES%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/update.xml
apz.disable_for_scroll_linked_effectsundefinedfalse
apz.fling_min_velocity_thresholdundefined0.5
apz.minimap.visibility.enabledundefinedfalse
apz.peek_messages.enabledundefinedtrue
apz.velocity_bias1.00.0
browser.chromeURLchrome://webapprt/content/webapp.xulchrome://browser/content/
browser.newtabpage.remote.content-signing-testundefinedfalse
browser.newtabpage.remote.keysundefined
browser.newtabpage.remote.versionundefined1
browser.offline-apps.notifyfalsetrue
browser.safebrowsing.downloads.remote.block_potentially_unwantedfalsetrue
browser.safebrowsing.downloads.remote.block_uncommonfalsetrue
browser.urlbar.daysBeforeHidingSuggestionsPromptundefined4
browser.urlbar.lastSuggestionsPromptDateundefined20160601
browser.urlbar.maxRichResults1210
browser.urlbar.unifiedcompletetrueundefined
devtools.devedition.promo.enabledfalsetrue
devtools.dom.enabledundefinedfalse
devtools.errorconsole.enabledfalseundefined
devtools.memory.custom-dominator-tree-displays{}undefined
devtools.memory.custom-label-displaysundefined{}
devtools.memory.custom-tree-map-displaysundefined{}
devtools.memory.max-individualsundefined1000
devtools.memory.max-retaining-pathsundefined10
dom.always_allow_move_resize_windowtrueundefined
dom.animations-api.element-animate.enabledundefinedtrue
dom.document.scrollingElement.enabledfalseundefined
dom.ipc.plugins.enabledtrueundefined
dom.max_chrome_script_run_time020
dom.max_script_run_time010
dom.mozAlarms.enabledtruefalse
dom.mozContacts.enabledfalseundefined
dom.mozPay.enabledfalseundefined
dom.mozTCPSocket.enabledtrueundefined
dom.node.rootNode.enabledundefinedfalse
dom.presentation.session_transport.data_channel.enableundefinedfalse
dom.requestcache.enabledfalseundefined
dom.sysmsg.enabledtruefalse
extensions.autoDisableScopes115
extensions.blocklist.detailsURLhttps://www.mozilla.com/%LOCALE%/blocklist/https://www.mozilla.org/%LOCALE%/blocklist/
extensions.blocklist.suppressUItrueundefined
extensions.enabledScopes1undefined
extensions.installDistroAddonsfalseundefined
extensions.showMismatchUIfalseundefined
extensions.webextensions.base-content-security-policyundefinedscript-src 'self' https://* moz-extension: blob: filesystem: 'unsafe-eval' 'unsafe-inline'; object-src 'self' https://* moz-extension: blob: filesystem:;
extensions.webextensions.default-content-security-policyundefinedscript-src 'self'; object-src 'self';
extensions.webservice.discoverURLhttps://services.addons.mozilla.org/%LOCALE%/firefox/discovery/pane/%VERSION%/%OS%/%COMPATIBILITY_MODE%https://discovery.addons.mozilla.org/%LOCALE%/firefox/discovery/pane/%VERSION%/%OS%/%COMPATIBILITY_MODE%
full-screen-api.transition.timeout5001000
geo.wifi.urihttps://location.services.mozilla.com/v1/geolocate?key=%MOZILLA_API_KEY%https://www.googleapis.com/geolocation/v1/geolocate?key=%GOOGLE_API_KEY%
gfx.canvas.azure.backendscairoskia
gfx.logging.painted-pixel-count.enabledundefinedfalse
javascript.options.mem.gc_refresh_frame_slices_enabledundefinedtrue
layers.child-process-shutdownundefinedtrue
layers.offmainthreadcomposition.enabledtrueundefined
layout.accessiblecaret.allow_dragging_across_other_caretundefinedtrue
layout.accessiblecaret.always_show_when_scrollingundefinedtrue
layout.accessiblecaret.bar.enabledtruefalse
layout.accessiblecaret.extendedvisibilityfalseundefined
layout.css.background-clip-text.enabledundefinedtrue
layout.css.color-adjust.enabledundefinedtrue
layout.css.prefixes.webkitfalsetrue
layout.css.sticky.enabledtrueundefined
layout.css.text-combine-upright-digits.enabledundefinedfalse
layout.css.text-combine-upright.enabledfalsetrue
layout.display-list.dump-contentundefinedfalse
layout.framevisibility.enabledundefinedtrue
layout.framevisibility.numscrollportheightsundefined1
layout.framevisibility.numscrollportwidthsundefined0
layout.imagevisibility.enabledtrueundefined
layout.imagevisibility.numscrollportheights1undefined
layout.imagevisibility.numscrollportwidths0undefined
media.decoder-doctor.notifications-allowedundefinedMediaWidevineNoWMFNoSilverlight
media.decoder-doctor.verboseundefinedfalse
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.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.atwebex.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,*.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,miriadaxdes.miriadax.net,certificacion.miriadax.net,miriadax.net
media.navigator.audio.full_duplexfalsetrue
network.http.max-connections256900
network.notify.IPv6undefinedtrue
network.predictor.enable-prefetchundefinedfalse
network.predictor.prefetch-force-valid-forundefined10
network.predictor.prefetch-min-confidenceundefined100
network.predictor.prefetch-rolling-load-countundefined10
places.database.growthIncrementKiB0undefined
plugin.allowed_types undefined
security.content.signature.root_hashundefined97:E8:BA:9C:F1:2F:B3:DE:53:CC:42:A4:E6:57:7E:D6:4D:F4:93:C2:47:B4:14:FE:A0:36:81:8D:38:23:56:0E
security.csp.debugfalseundefined
security.onecrl.via.amoundefinedtrue
security.pki.name_matching_modeundefined1
security.pki.sha1_enforcement_level03
security.webauth.u2f.softtokenfalseundefined
security.webauth.u2f.usbtokenfalseundefined
security.webauth.u2f_enable_softtokenundefinedfalse
security.webauth.u2f_enable_usbtokenundefinedfalse
services.kinto.addons.checkedundefined0
services.kinto.addons.collectionundefinedaddons
services.kinto.changes.pathundefined/buckets/monitor/collections/changes/records
services.kinto.gfx.checkedundefined0
services.kinto.gfx.collectionundefinedgfx
services.kinto.plugins.checkedundefined0
services.kinto.plugins.collectionundefinedplugins
services.kinto.update_enabledundefinedfalse
toolkit.asyncshutdown.crash_timeoutundefined60000
toolkit.asyncshutdown.timeout.crash60000undefined
webapprt.app_update_interval86400undefined
xpinstall.enabledfalseundefined
Default pref Javascript files
PrefFirefox 47.0.1Firefox 48.0 beta 5
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.jspresentnot present