This is difference between the default preference of Firefox 35.0 beta 5 and one of 34.0.5.

Default pref Javascript files (Firefox 34.0.5 for Linux x86_64):
(omni.ja){/greprefs.js,/defaults/pref/services-sync.js}, (browser/omni.ja)/defaults/preferences/{firefox.js,firefox-branding.js,firefox-l10n.js}, (webapprt/omni.ja)/defaults/preferences/prefs.js
Default pref Javascript files (Firefox 35.0 beta 5 for Linux x86_64):
(omni.ja){/greprefs.js,/defaults/pref/services-sync.js}, (browser/omni.ja)/defaults/preferences/{firefox.js,firefox-branding.js,firefox-l10n.js}, (webapprt/omni.ja)/defaults/preferences/prefs.js
PrefFirefox 34.0.5Firefox 36.0 beta 5
app.update.badgeundefinedfalse
apz.axis_lock.breakout_angleundefined0.3926991
apz.axis_lock.breakout_thresholdundefined0.03125
apz.axis_lock.direct_pan_angleundefined1.047197
apz.axis_lock.lock_angleundefined0.5235987
apz.axis_lock.modeundefined0
apz.axis_lock_mode0undefined
apz.smooth_scroll_repaint_intervalundefined75
bidi.edit.delete_immediatelyfalsetrue
browser.aboutHomeSnippets.updateUrlhttps://snippets.mozilla.com/%STARTPAGE_VERSION%/%NAME%/%VERSION%/%APPBUILDID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/https://snippets.cdn.mozilla.net/%STARTPAGE_VERSION%/%NAME%/%VERSION%/%APPBUILDID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/
browser.apps.URLundefinedhttps://marketplace.firefox.com/discovery/
browser.devedition.theme.enabledundefinedfalse
browser.devedition.theme.showCustomizeButtonundefinedfalse
browser.search.defaultenginename.USchrome://browser-region/locale/region.propertiesdata:text/plain,browser.search.defaultenginename.US=Yahoo
browser.search.geoSpecificDefaultsundefinedtrue
browser.search.order.US.1chrome://browser-region/locale/region.propertiesdata:text/plain,browser.search.order.US.1=Yahoo
browser.search.order.US.2chrome://browser-region/locale/region.propertiesdata:text/plain,browser.search.order.US.2=Google
browser.search.order.US.3chrome://browser-region/locale/region.propertiesdata:text/plain,browser.search.order.US.3=Bing
browser.tabs.remotefalseundefined
browser.tabs.remote.desktopbehaviorundefinedtrue
browser.uitour.whitelist.add.260www.mozilla.org,support.mozilla.orgundefined
browser.uitour.whitelist.add.340about:homeundefined
browser.uitour.whitelist.add.341www.mozilla.org,support.mozilla.org,about:homeundefined
browser.urlbar.unifiedcompleteundefinedfalse
canvas.filters.enabledundefinedfalse
datareporting.healthreport.service.providerCategorieshealthreport-js-provider-defaulthealthreport-js-provider-default,healthreport-js-provider-beta
devtools.devedition.promo.enabledfalsetrue
devtools.editor.enableCodeFoldingundefinedtrue
devtools.scratchpad.enableCodeFoldingtrueundefined
devtools.styleeditor.source-maps-enabledfalsetrue
devtools.timeline.enabledundefinedfalse
dns.ttl-experiment.enabledundefinedtrue
dns.ttl-experiment.variantundefined0
dom.abortablepromise.enabledundefinedfalse
dom.enable_resource_timingfalsetrue
dom.imagecapture.enabledundefinedfalse
dom.ipc.plugins.flash.disable-protected-modeundefinedfalse
dom.unsafe_legacy_crypto.enabledtrueundefined
dom.window_experimental_bindingstrueundefined
geo.wifi.logging.enabledfalseundefined
gfx.downloadable_fonts.woff2.enabledundefinedfalse
identity.fxaccounts.migrateToDevEditionundefinedfalse
layout.css.clip-path-shapes.enabledundefinedfalse
layout.css.filters.enabledfalsetrue
layout.css.font-loading-api.enabledundefinedfalse
layout.css.masking.enabledfalsetrue
layout.css.object-fit-and-position.enabledundefinedfalse
layout.event-regions.enabledundefinedfalse
loop.CSPdefault-src 'self' about: file: chrome:; img-src 'self' data: http://www.gravatar.com/ about: file: chrome:; font-src 'none'; connect-src wss://*.tokbox.com https://*.opentok.com https://*.tokbox.com wss://*.mozilla.com https://*.mozilla.org wss://*.mozaws.netdefault-src 'self' about: file: chrome:; img-src 'self' data: http://www.gravatar.com/ about: file: chrome:; font-src 'none'; connect-src wss://*.tokbox.com https://*.opentok.com https://*.tokbox.com wss://*.mozilla.com https://*.mozilla.org wss://*.mozaws.net; media-src blob:
loop.gettingStarted.seenundefinedfalse
loop.gettingStarted.urlundefinedhttps://www.mozilla.org/%LOCALE%/firefox/%VERSION%/hello/start
loop.learnMoreUrlundefinedhttps://www.firefox.com/hello/
loop.legal.ToS_urlhttps://hello.firefox.com/legal/terms/https://www.mozilla.org/about/legal/terms/firefox-hello/
loop.legal.privacy_urlhttps://www.mozilla.org/privacy/https://www.mozilla.org/privacy/firefox-hello/
loop.ringtonechrome://browser/content/loop/shared/sounds/Firefox-Long.oggchrome://browser/content/loop/shared/sounds/ringtone.ogg
loop.rooms.enabledundefinedtrue
loop.serverhttps://loop.services.mozilla.comhttps://loop.services.mozilla.com/v0
loop.soft_start_hostnamesoft-start.loop.services.mozilla.comundefined
loop.soft_start_ticket_number-1undefined
loop.support_urlundefinedhttps://support.mozilla.org/kb/group-conversations-firefox-hello-webrtc
loop.throttledtrueundefined
loop.throttled2undefinedfalse
media.fragmented-mp4.enabledfalsetrue
media.peerconnection.ice.loopbackundefinedfalse
media.peerconnection.trickle_icetrueundefined
network.http.altsvc.enabledundefinedfalse
network.http.altsvc.oeundefinedfalse
network.http.network-changed.timeoutundefined5
network.http.spdy.enabled.http2undefinedfalse
network.http.spdy.enabled.http2draftfalsetrue
network.notify.changedundefinedtrue
plugins.hideMissingPluginsNotificationfalseundefined
plugins.notifyMissingFlashtrueundefined
privacy.panicButton.enabledLocalesast da de en-GB en-US es-AR es-CL es-ES es-MX fi fr fy-NL he hu it ja ja-JP-mac ko lv nb-NO nn-NO pa-IN pl pt-BR rm ru sk sl zh-TWundefined
privacy.panicButton.useLocaleListfalseundefined
security.cert_pinning.process_headers_from_non_builtin_rootsundefinedfalse
services.sync.prefs.sync.privacy.trackingprotection.enabledundefinedtrue
social.share.activationPanelEnabledundefinedtrue
social.shareDirectoryundefinedhttps://activations.cdn.mozilla.net/sharePanel.html
startup.homepage_override_urlhttps://www.mozilla.org/%LOCALE%/firefox/%VERSION%/whatsnew/?oldversion=%OLD_VERSION%
svg.path-caching.enabledundefinedtrue
touchcaret.distance.threshold1500undefined
touchcaret.inflatesize.thresholdundefined40
urlclassifier.gethash.timeout_msundefined5000
xpinstall.whitelist.addaddons.mozilla.orgundefined
xpinstall.whitelist.add.180marketplace.firefox.comundefined