This is difference between the default preference of Firefox 14beta1 and one of 13.0.

Default pref Javascript files (Firefox 13.0 for linux):
(omni.ja){/greprefs.js,/defaults/pref/{firefox.js,firefox-branding.js,firefox-l10n.js,services-sync.js}}
Default pref Javascript files (Firefox 14beta1 for linux):
(omni.ja){/greprefs.js,/defaults/preferences/{firefox.js,firefox-branding.js,firefox-l10n.js,services-sync.js}}
PrefFirefox 13.0Firefox 14 beta 1
browser.download.panel.removeFinishedDownloadsundefinedfalse
browser.download.useToolkitUIundefinedtrue
browser.identity.ssl_domain_display10
browser.urlbar.autoFillfalsetrue
devtools.layoutview.enabledundefinedfalse
devtools.layoutview.openundefinedfalse
dom.mozSettings.enabledundefinedfalse
dom.paris_bindingsundefinedtrue
editor.use_csstruefalse
font.size.inflation.lineThresholdundefined400
full-screen-api.pointer-lock.enabledundefinedtrue
gfx.filter.nearest.force-enabledundefinedfalse
gfx.show_checkerboard_patterntrueundefined
gfx.work-around-driver-bugsundefinedtrue
image.mem.max_decoded_image_kbundefined256000
memory.ghost_window_timeout_secondsundefined60
network.http.assoc-req.enforceundefinedfalse
network.http.pipelining.aggressiveundefinedfalse
network.http.pipelining.max-optimistic-requestsundefined4
network.http.pipelining.maxrequests432
network.http.pipelining.maxsizeundefined300000
network.http.pipelining.read-timeoutundefined30000
network.http.pipelining.reschedule-on-timeoutundefinedtrue
network.http.pipelining.reschedule-timeoutundefined1500
services.sync.prefs.sync.browser.newtabpage.enabledtrueundefined
services.sync.prefs.sync.browser.urlbar.autoFilltrueundefined
services.sync.prefs.sync.general.smoothScrolltrueundefined
toolkit.telemetry.debugSlowSqlundefinedfalse