This is difference between the default preference of Firefox 32.0 beta 4 and one of 31.0.

Default pref Javascript files (Firefox 31.0 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 32.0 beta 4 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 31.0Firefox 32.0 beta 4
accessibility.typeaheadfind.matchesCountLimitundefined100
accessibility.typeaheadfind.matchesCountTimeoutundefined250
apz.test.logging_enabledundefinedfalse
browser.cache.disk.preload_chunk_countundefined4
browser.cache.frecency_half_life_hoursundefined6
browser.cache.use_new_backend_tempundefinedtrue
browser.frames.enabledtrueundefined
browser.newtabpage.directory.sourceundefinedchrome://global/content/directoryLinks.json
browser.newtabpage.directorySourcedata:application/json,{}undefined
browser.search.param.ms-pcMOZIundefined
browser.search.param.yahoo-fr-cjktmoz35undefined
browser.sessionstore.cleanup.forget_closed_afterundefined1209600000
browser.slowStartup.timeThreshold5000045000
browser.translation.neverForLanguagesundefined
browser.translation.ui.showundefinedfalse
browser.uitour.whitelist.add.340undefinedabout:home
camera.control.autofocus_moving_callback.enabledfalsetrue
camera.control.face_detection.enabledfalsetrue
canvas.focusring.enabledfalsetrue
datareporting.healthreport.service.providerCategorieshealthreport-js-provider-defaulthealthreport-js-provider-default,healthreport-js-provider-beta
devtools.command-button-screenshot.enabledundefinedfalse
devtools.inspector.showUserAgentStylesundefinedfalse
devtools.scratchpad.enableAutocompletionundefinedtrue
devtools.selfxss.countundefined0
devtools.styleeditor.showMediaSidebarundefinedfalse
devtools.toolbox.toolbarSpec["splitconsole", "paintflashing toggle","tilt toggle","scratchpad","resize toggle","eyedropper"]["splitconsole", "paintflashing toggle","tilt toggle","scratchpad","resize toggle","eyedropper","screenshot --fullpage"]
devtools.webide.enabledundefinedfalse
dom.animations-api.core.enabledundefinedfalse
dom.event.highrestimestamp.enabledundefinedfalse
dom.forms.autocomplete.experimentalundefinedfalse
dom.forms.requestAutocompleteundefinedfalse
dom.image.srcset.enabledundefinedfalse
dom.ipc.plugins.unloadTimeoutSecsundefined30
dom.keyboardevent.code.enabledundefinedfalse
dom.mms.sendRetryInterval30000010000,60000,180000
dom.serviceWorkers.enabledundefinedfalse
dom.webcrypto.enabledundefinedfalse
dom.window_experimental_bindingsundefinedtrue
gfx.draw-color-barsundefinedfalse
intl.charsetmenu.browser.cacheundefined
intl.charsetmenu.browser.cache.size5undefined
intl.charsetmenu.browser.more1ISO-8859-1, ISO-8859-15, IBM850, macintosh, windows-1252, ISO-8859-14, ISO-8859-7, x-mac-greek, windows-1253, x-mac-icelandic, ISO-8859-10, ISO-8859-3undefined
intl.charsetmenu.browser.more2ISO-8859-4, ISO-8859-13, windows-1257, IBM852, ISO-8859-2, x-mac-ce, windows-1250, x-mac-croatian, IBM855, ISO-8859-5, ISO-IR-111, KOI8-R, x-mac-cyrillic, windows-1251, IBM866, KOI8-U, x-mac-ukrainian, ISO-8859-16, x-mac-romanianundefined
intl.charsetmenu.browser.more3GB2312, gbk, gb18030, HZ-GB-2312, ISO-2022-CN, Big5, Big5-HKSCS, x-euc-tw, EUC-JP, ISO-2022-JP, Shift_JIS, EUC-KR, x-johab, ISO-2022-KRundefined
intl.charsetmenu.browser.more4armscii-8, TIS-620, ISO-8859-11, windows-874, IBM857, ISO-8859-9, x-mac-turkish, windows-1254, x-viet-tcvn5712, VISCII, x-viet-vps, windows-1258, x-mac-devanagari, x-mac-gujarati, x-mac-gurmukhiundefined
intl.charsetmenu.browser.more5ISO-8859-6, windows-1256, ISO-8859-8-I, windows-1255, ISO-8859-8, IBM862undefined
intl.charsetmenu.browser.staticchrome://global/locale/intl.propertiesundefined
intl.charsetmenu.composer.cacheundefined
intl.charsetmenu.maileditchrome://global/locale/intl.propertiesundefined
intl.charsetmenu.mailview.cacheundefined
javascript.options.native_regexpundefinedtrue
layers.async-pan-zoom.enabledundefinedfalse
layers.bench.enabledundefinedfalse
layers.low-precision-bufferundefinedfalse
layers.tile-heightundefined256
layers.tile-widthundefined256
layout.css.box-decoration-break.enabledundefinedtrue
layout.css.grid.enabledundefinedfalse
layout.css.mix-blend-mode.enabledfalsetrue
layout.css.scope-pseudo.enabledfalsetrue
layout.css.sticky.enabledfalsetrue
layout.css.supports-rule.enabledtrueundefined
media.eme.enabledundefinedfalse
media.navigator.load_adaptfalsetrue
media.peerconnection.video.max_bitrateundefined2000
media.peerconnection.video.min_bitrateundefined200
media.peerconnection.video.start_bitrateundefined300
media.webrtc.debug.aec_dump_max_sizeundefined4194304
media.webrtc.debug.aec_log_dirundefined
media.webrtc.debug.log_fileundefined
media.webrtc.debug.multi_logundefinedfalse
media.webrtc.debug.trace_maskundefined0
media.webspeech.synth.enabledundefinedfalse
network.predictor.enable-hover-on-sslundefinedfalse
network.predictor.enabledundefinedfalse
network.predictor.max-db-sizeundefined157286400
network.predictor.max-queue-sizeundefined50
network.predictor.page-degradation.dayundefined0
network.predictor.page-degradation.maxundefined50
network.predictor.page-degradation.monthundefined10
network.predictor.page-degradation.weekundefined5
network.predictor.page-degradation.yearundefined25
network.predictor.preconnect-min-confidenceundefined90
network.predictor.preresolve-min-confidenceundefined60
network.predictor.preserveundefined80
network.predictor.redirect-likely-confidenceundefined75
network.predictor.subresource-degradation.dayundefined1
network.predictor.subresource-degradation.maxundefined100
network.predictor.subresource-degradation.monthundefined25
network.predictor.subresource-degradation.weekundefined10
network.predictor.subresource-degradation.yearundefined50
network.proxy.proxy_over_tlsundefinedtrue
network.seer.enable-hover-on-sslfalseundefined
network.seer.enabledfalseundefined
network.seer.max-db-size157286400undefined
network.seer.max-queue-size50undefined
network.seer.page-degradation.day0undefined
network.seer.page-degradation.max50undefined
network.seer.page-degradation.month10undefined
network.seer.page-degradation.week5undefined
network.seer.page-degradation.year25undefined
network.seer.preconnect-min-confidence90undefined
network.seer.preresolve-min-confidence60undefined
network.seer.preserve80undefined
network.seer.redirect-likely-confidence75undefined
network.seer.subresource-degradation.day1undefined
network.seer.subresource-degradation.max100undefined
network.seer.subresource-degradation.month25undefined
network.seer.subresource-degradation.week10undefined
network.seer.subresource-degradation.year50undefined
plugins.update.urlhttps://www.mozilla.org/%LOCALE%/plugincheck/https://www.mozilla.org/%LOCALE%/plugincheck/?utm_source=firefox-browser&utm_medium=firefox-browser&utm_campaign=plugincheck-update
security.cert_pinning.enforcement_levelundefined1
security.csp.newbackend.enableundefinedfalse
selectioncaret.enabledundefinedfalse
selectioncaret.inflatesize.thresholdundefined40
svg.new-getBBox.enabledundefinedfalse
svg.svg-iframe.enabledundefinedfalse
touchcaret.distance.thresholdundefined1500
touchcaret.enabledundefinedfalse
touchcaret.expiration.timeundefined3000