This is difference between the default preference of Firefox 44.0 beta 4 and one of 43.0.3.

Preference difference
PrefFirefox 43.0.3Firefox 44.0 beta 4
apz.drag.enabledundefinedfalse
apz.fling_snap_frictionundefined0.015
browser.push.warning.infoURLhttps://www.mozilla.org/%LOCALE%/firefox/push/undefined
browser.safebrowsing.provider.mozilla.nextupdatetimeundefined1
browser.tabs.crashReporting.emailundefined
browser.tabs.crashReporting.emailMeundefinedfalse
browser.tabs.crashReporting.includeURLundefinedfalse
browser.tabs.crashReporting.sendReportundefinedtrue
browser.tabs.dontfocusfordialogsundefinedtrue
clipboard.plainTextOnlyundefinedfalse
datareporting.healthreport.service.providerCategorieshealthreport-js-provider-defaulthealthreport-js-provider-default,healthreport-js-provider-beta
devtools.command-button-measure.enabledundefinedfalse
devtools.debugger.remote-enabledtruefalse
devtools.defaultColorUnithexauthored
devtools.devedition.promo.enabledfalsetrue
devtools.inspector.markupPreviewfalseundefined
devtools.jsonview.enabledundefinedfalse
devtools.memory.custom-breakdownsundefined{}
devtools.migration.warningsundefinedfalse
devtools.toolbox.toolbarSpec["splitconsole", "paintflashing toggle","tilt toggle","scratchpad","resize toggle","eyedropper","screenshot --fullpage", "rulers"]["splitconsole", "paintflashing toggle","tilt toggle","scratchpad","resize toggle","eyedropper","screenshot --fullpage", "rulers", "measure"]
devtools.webconsole.filter.serviceworkersfalsetrue
devtools.webide.autosaveFilesundefinedtrue
devtools.webide.sidebarstrueundefined
dom.disable_image_src_setfalseundefined
dom.mouseEvent.offsetXY.enabledtrueundefined
dom.presentation.discovery.enabledtruefalse
dom.push.quotaUpdateDelayundefined3000
dom.require_user_interaction_for_beforeunloadundefinedtrue
dom.serviceWorkers.enabledfalsetrue
dom.serviceWorkers.idle_extended_timeoutundefined300000
dom.serviceWorkers.idle_timeoutundefined30000
dom.serviceWorkers.interception.enabledfalsetrue
dom.serviceWorkers.interception.opaque.enabledfalsetrue
dom.serviceWorkers.openWindow.enabledundefinedtrue
dom.serviceWorkers.testUpdateOverOneDayundefinedfalse
dom.workers.sharedWorkers.enabledtrueundefined
extensions.systemAddon.update.urlundefinedhttps://aus5.mozilla.org/update/3/SystemAddons/%VERSION%/%BUILD_ID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/update.xml
gfx.font_rendering.fontconfig.fontlist.enabledfalsetrue
gfx.font_rendering.fontconfig.max_generic_substitutionsundefined3
gfx.offscreencanvas.enabledundefinedfalse
javascript.options.throw_on_asmjs_validation_failureundefinedfalse
layers.amd-switchable-gfx.enabledundefinedtrue
layout.accessiblecaret.height47.036.0
layout.accessiblecaret.margin-left-23.5-18.5
layout.accessiblecaret.use_long_tap_injectorundefinedtrue
layout.accessiblecaret.width44.034.0
layout.css.prefixes.webkitundefinedfalse
layout.css.unicode-range.enabledfalseundefined
layout.imagevisibility.enabled_for_browser_elements_onlyfalseundefined
loop.contacts.gravatars.promotrueundefined
loop.contacts.gravatars.showfalseundefined
loop.debug.websocketfalseundefined
media.ffmpeg.enabledundefinedtrue
media.fragmented-mp4.enabledtrueundefined
media.fragmented-mp4.ffmpeg.enabledtrueundefined
media.fragmented-mp4.gmp.enabledfalseundefined
media.fragmented-mp4.use-blank-decoderfalseundefined
media.gmp.decoder.aacundefined2
media.gmp.decoder.enabledundefinedfalse
media.gmp.decoder.h264undefined2
media.mediasource.webm.audio.enabledundefinedtrue
media.mp4.enabledundefinedtrue
media.navigator.audio.fake_frequencyundefined1000
media.use-blank-decoderundefinedfalse
media.youtube-ua.overridetrueundefined
media.youtube-ua.override.from43undefined
media.youtube-ua.override.to42undefined
network.http.accept-encoding.secureundefinedgzip, deflate, br
network.http.pacing.requests.burst3210
network.http.pacing.requests.hz10080
network.http.packaged-apps-developer-modefalseundefined
network.http.signed-packages.enabledundefinedfalse
network.http.spdy.pull-allowanceundefined12582912
privacy.userContext.enabledundefinedfalse
security.insecure_password.ui.enabledundefinedfalse
security.tls.insecure_fallback_hosts.use_static_listtrueundefined
security.tls.unrestricted_rc4_fallbacktruefalse
toolkit.pageThumbs.minHeightundefined190
toolkit.pageThumbs.minWidthundefined280
toolkit.pageThumbs.screenSizeDivisorundefined7
Default pref Javascript files
FileFirefox 43.0.3Firefox 44.0 beta 4
browser/omni.ja!/defaults/preferences/devtools.jsN/Apresent
browser/omni.ja!/defaults/preferences/firefox-branding.jstools.jspresentpresent
browser/omni.ja!/defaults/preferences/firefox-l10n.jstools.jspresentpresent
browser/omni.ja!/defaults/preferences/firefox.jstools.jspresentpresent
browser/omni.ja!/defaults/preferences/webide-prefs.jstools.jspresentpresent
omni.ja!/defaults/pref/services-sync.jstools.jspresentpresent
omni.ja!/greprefs.jstools.jspresentpresent
webapprt/omni.ja!/defaults/preferences/prefs.jstools.jspresentpresent