This is difference between the default preference of Firefox 36.0 beta 2 and one of 35.0.

Default pref Javascript files (Firefox 35.0 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 36.0 beta 2 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 35.0Firefox 36.0 beta 2
app.update.certs.1.commonNameaus3.mozilla.orgaus4.mozilla.org
app.update.certs.1.issuerNameCN=Thawte SSL CA,O="Thawte, Inc.",C=USCN=DigiCert Secure Server CA,O=DigiCert Inc,C=US
app.update.certs.2.commonNameaus3.mozilla.orgaus4.mozilla.org
app.update.certs.2.issuerNameCN=DigiCert Secure Server CA,O=DigiCert Inc,C=USCN=Thawte SSL CA,O="Thawte, Inc.",C=US
app.update.urlhttps://aus3.mozilla.org/update/3/%PRODUCT%/%VERSION%/%BUILD_ID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/update.xmlhttps://aus4.mozilla.org/update/3/%PRODUCT%/%VERSION%/%BUILD_ID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/update.xml
apz.fling_curve_function_x1undefined0.0
apz.fling_curve_function_x2undefined1.0
apz.fling_curve_function_y1undefined0.0
apz.fling_curve_function_y2undefined1.0
apz.fling_curve_threshold_inches_per_msundefined-1.0
apz.overscroll.fling_friction0.02undefined
apz.overscroll.fling_stopped_threshold0.4undefined
apz.overscroll.snap_back.mass1000.0undefined
apz.overscroll.snap_back.spring_friction0.1undefined
apz.overscroll.snap_back.spring_stiffness0.6undefined
apz.overscroll.spring_frictionundefined0.015
apz.overscroll.spring_stiffnessundefined0.001
apz.overscroll.stop_distance_thresholdundefined5.0
apz.overscroll.stop_velocity_thresholdundefined0.01
browser.defaultbrowser.notificationbarundefinedfalse
browser.preferences.inContentfalsetrue
browser.search.geoip.timeoutundefined2000
browser.search.geoip.urlundefinedhttps://location.services.mozilla.com/v1/country?key=%MOZILLA_API_KEY%
browser.urlbar.default.behavior0undefined
browser.urlbar.suggest.bookmarkundefinedtrue
browser.urlbar.suggest.historyundefinedtrue
browser.urlbar.suggest.history.onlyTypedundefinedfalse
browser.urlbar.suggest.openpageundefinedtrue
datareporting.healthreport.service.providerCategorieshealthreport-js-provider-defaulthealthreport-js-provider-default,healthreport-js-provider-beta
devtools.apps.forbidden-permissionsundefinedembed-apps,engineering-mode,embed-widgets
devtools.devedition.promo.enabledfalsetrue
devtools.performance.ui.show-timeline-memoryundefinedfalse
devtools.performance_dev.enabledundefinedfalse
dns.ttl-experiment.enabledtrueundefined
dns.ttl-experiment.variant0undefined
dom.beforeAfterKeyboardEvent.enabledundefinedfalse
dom.meta-viewport.enabledundefinedfalse
dom.vr.add-test-devicesundefined1
dom.vr.enabledundefinedfalse
font.alias-listsans,sans-serif,serif,monospaceundefined
image.mem.hard_limit_decoded_image_kb0undefined
image.mem.min_discard_timeout_ms10000undefined
image.mem.surfacecache.discard_factorundefined1
image.mem.surfacecache.max_size_kb1024001048576
image.mem.surfacecache.size_factor644
javascript.options.mem.gc_min_empty_chunk_count10
layers.gralloc.disableundefinedfalse
layers.progressive-paintundefinedfalse
layers.tiles.adjustundefinedtrue
layout.css.display-contents.enabledundefinedfalse
layout.css.isolation.enabledundefinedtrue
layout.css.object-fit-and-position.enabledfalsetrue
layout.css.scroll-behavior.enabledfalsetrue
layout.css.scroll-behavior.property-enabledundefinedtrue
layout.css.unicode-range.enabledundefinedfalse
layout.css.will-change.enabledfalsetrue
loop.ping.intervalundefined1800000
loop.ping.timeoutundefined10000
loop.soft_start_hostnamesoft-start.loop.services.mozilla.comundefined
loop.soft_start_ticket_number-1undefined
loop.throttled2trueundefined
media.cache_readahead_limitundefined999999
media.cache_resume_thresholdundefined999999
media.getusermedia.screensharing.allowed_domainswebex.com,*.webex.com,collaborate.com,*.collaborate.com,projectsquared.com,*.projectsquared.com,*.room.co,room.co,beta.talky.io,talky.iowebex.com,*.webex.com,collaborate.com,*.collaborate.com,projectsquared.com,*.projectsquared.com,*.room.co,room.co,beta.talky.io,talky.io,*.clearslide.com,example.com
media.mediasource.mp4.enabledundefinedfalse
media.mediasource.webm.enabledundefinedtrue
media.mediasource.youtubeonlyundefinedtrue
network.IDN.blacklist_chars  ¼½¾ǃː̷̸։׃״؉؊٪۔܁܂܃܄ᅟᅠ᜵           ​․‧

 ‹›⁁⁄⁒ ⅓⅔⅕⅖⅗⅘⅙⅚⅛⅜⅝⅞⅟∕∶⎮╱⧶⧸⫻⫽⿰⿱⿲⿳⿴⿵⿶⿷⿸⿹⿺⿻　。〔〕〳ㅤ㈝㈞㎮㎯㏆㏟꞉︔︕︿﹝﹞．／｡ﾠ�  ¼½¾ǃː̷̸։׃״؉؊٪۔܁܂܃܄ᅟᅠ᜵           ​‎‏․‧

‪‫‬‭‮ ‹›⁁⁄⁒ ⅓⅔⅕⅖⅗⅘⅙⅚⅛⅜⅝⅞⅟∕∶⎮╱⧶⧸⫻⫽⿰⿱⿲⿳⿴⿵⿶⿷⿸⿹⿺⿻　。〔〕〳ㅤ㈝㈞㎮㎯㏆㏟꞉︔︕︿﹝﹞．／｡ﾠ�
network.dns.get-ttlundefinedtrue
network.http.spdy.enabled.http2falsetrue
network.http.spdy.enabled.v3trueundefined
print.enable_e10s_testingundefinedfalse
privacy.donottrackheader.value1undefined
security.ssl.errorReporting.automaticundefinedfalse
security.ssl.errorReporting.enabledundefinedtrue
security.ssl.errorReporting.urlundefinedhttps://data.mozilla.com/submit/sslreports
selectioncaret.noneditableundefinedfalse
services.sync.prefs.sync.browser.newtabpage.enabledundefinedtrue
services.sync.prefs.sync.browser.newtabpage.enhancedundefinedtrue
services.sync.prefs.sync.browser.newtabpage.pinnedundefinedtrue
services.sync.prefs.sync.browser.urlbar.default.behaviortrueundefined
services.sync.prefs.sync.privacy.donottrackheader.valuetrueundefined
social.share.activationPanelEnabledfalsetrue
webgl.lose-context-on-memory-preasurefalseundefined
webgl.lose-context-on-memory-pressureundefinedfalse