This is difference between the default preference of Firefox 22.0 beta 3 and one of 21.0.

Default pref Javascript files (Firefox 21.0 for linux):
(omni.ja){/greprefs.js,/defaults/pref/services-sync.js}, (browser/omni.ja)defaults/preferences/{firefox.js,firefox-branding.js,firefox-l10n.js}
Default pref Javascript files (Firefox 22.0 beta 3 for linux):
(omni.ja){/greprefs.js,/defaults/pref/services-sync.js}, (browser/omni.ja)defaults/preferences/{firefox.js,firefox-branding.js,firefox-l10n.js}
PrefFirefox 21.0Firefox 22.0 beta 3
breakpad.reportURLhttp://crash-stats.mozilla.com/report/index/https://crash-stats.mozilla.com/report/index/
browser.geolocation.warning.infoURLhttp://www.mozilla.com/%LOCALE%/firefox/geolocation/https://www.mozilla.org/%LOCALE%/firefox/geolocation/
datareporting.healthreport.infoURLhttp://www.mozilla.org/legal/privacy/firefox.html#health-reporthttps://www.mozilla.org/legal/privacy/firefox.html#health-report
datareporting.healthreport.logging.dumpEnabledundefinedfalse
datareporting.healthreport.logging.dumpLevelundefinedDebug
datareporting.healthreport.service.providerCategorieshealthreport-js-providerhealthreport-js-provider-default,healthreport-js-provider-beta
devtools.debugger.chrome-debugging-hostundefinedlocalhost
devtools.debugger.chrome-debugging-portundefined6080
devtools.debugger.ui.panes-instruments-widthundefined300
devtools.debugger.ui.panes-sources-widthundefined200
devtools.debugger.ui.stackframes-width200undefined
devtools.debugger.ui.variables-width300undefined
devtools.fontinspector.enabledundefinedtrue
devtools.themeundefinedlight
devtools.toolbox.sideEnabledfalsetrue
devtools.toolbox.toolbarSpec["tilt toggle","scratchpad","resize toggle"]["paintflashing toggle","tilt toggle","scratchpad","resize toggle"]
dom.debug.propagate_gesture_events_through_contentundefinedfalse
dom.experimental_bindingstrueundefined
dom.mms.retrievalRetryCountundefined3
dom.mms.retrievalRetryIntervalundefined300000
dom.mms.retrieval_modeundefinedmanual
dom.omit_components_in_contentundefinedtrue
dom.webnotifications.enabledundefinedtrue
full-screen-api.content-onlyundefinedfalse
full-screen-api.exit-on-deactivatetrueundefined
gfx.font_rendering.graphite.enabledfalsetrue
gl.msaa-levelundefined2
image.high_quality_upscaling.max_sizeundefined20971520
image.multithreaded_decoding.enabledundefinedtrue
image.multithreaded_decoding.limitundefined-1
javascript.options.asmjsundefinedtrue
layout.css.flexbox.enabledfalsetrue
layout.css.supports-rule.enabledfalsetrue
layout.imagevisibility.enabledundefinedfalse
media.dash.enabledfalseundefined
media.navigator.video.default_fpsundefined30
media.navigator.video.default_heightundefined480
media.navigator.video.default_minfpsundefined10
media.navigator.video.default_widthundefined640
media.peerconnection.enabledfalsetrue
media.webspeech.recognition.enableundefinedfalse
network.IDN.restriction_profileundefinedmoderate
network.IDN.use_whitelistundefinedtrue
network.IDN.whitelist.comtrueundefined
network.IDN.whitelist.nametrueundefined
network.IDN.whitelist.nettrueundefined
network.enableIDNtrueundefined
plain_text.wrap_long_linesundefinedtrue
security.notification_enable_delay0500
social.directoriesundefinedhttps://addons.mozilla.org
social.remote-install.enabledundefinedfalse
social.whitelistundefined
toolkit.crashreporter.infoURLhttp://www.mozilla.com/legal/privacy/firefox.html#crash-reporterhttps://www.mozilla.org/legal/privacy/firefox.html#crash-reporter
toolkit.telemetry.infoURLhttp://www.mozilla.com/legal/privacy/firefox.html#telemetryhttps://www.mozilla.org/legal/privacy/firefox.html#telemetry
webgl.msaa-level2undefined