This is difference between the default preference of Firefox 68.0 beta 4 and one of 67.0.

Preference difference
PrefFirefox 68.0.1Firefox 69.0 beta 6
app.releaseNotesURLhttps://www.mozilla.org/%LOCALE%/firefox/%VERSION%/releasenotes/?utm_source=firefox-browser&utm_medium=firefox-browser&utm_campaign=whatsnewhttps://www.mozilla.org/%LOCALE%/firefox/%VERSION%beta/releasenotes/?utm_source=firefox-browser&utm_medium=firefox-browser&utm_campaign=whatsnew
app.update.altwindowtypeBrowser:Aboutundefined
app.update.doorhangertrueundefined
app.update.idletime60undefined
app.update.silentfalseundefined
app.update.url.detailshttps://www.mozilla.org/%LOCALE%/firefox/noteshttps://www.mozilla.org/%LOCALE%/firefox/beta/notes
app.update.url.manualhttps://www.mozilla.org/firefox/https://www.mozilla.org/firefox/beta
apz.fling_curve_function_x10.0undefined
apz.fling_curve_function_x21.0undefined
apz.fling_curve_function_y10.0undefined
apz.fling_curve_function_y21.0undefined
apz.keyboard.enabledtrueundefined
apz.max_velocity_queue_size5undefined
apz.pinch_lock.buffer_max_age50undefined
beacon.enabledtrueundefined
browser.cache.offline.enabletrueundefined
browser.contentblocking.database.enabledundefinedtrue
browser.contentblocking.reportBreakage.enabledfalsetrue
browser.hiddenWindowChromeURLchrome://browser/content/hiddenWindow.xulchrome://browser/content/hiddenWindowMac.xhtml
browser.messaging-system.whatsNewPanel.enabledundefinedfalse
browser.newtabpage.activity-stream.prerendertrueundefined
browser.privatebrowsing.searchUItrueundefined
browser.search.reset.enabledfalseundefined
browser.search.reset.whitelistundefined
browser.tabs.remote.enforceRemoteTypeRestrictionsundefinedfalse
browser.tabs.remote.separatePrivilegedMozillaWebContentProcessundefinedfalse
browser.tabs.remote.separatedMozillaDomainsundefinedaddons.mozilla.org,accounts.firefox.com
browser.tabs.remote.useCrossOriginOpenerPolicyfalseundefined
browser.urlbar.openViewOnFocusundefinedfalse
canvas.capturestream.enabledtrueundefined
canvas.filters.enabledtrueundefined
canvas.focusring.enabledtrueundefined
canvas.hitregions.enabledfalseundefined
canvas.path.enabledtrueundefined
device.sensors.ambientLight.enabledfalseundefined
device.sensors.enabledtrueundefined
device.sensors.motion.enabledtrueundefined
device.sensors.orientation.enabledtrueundefined
device.sensors.proximity.enabledfalseundefined
devtools.aboutdebugging.new-enabledfalsetrue
devtools.browserconsole.filterContentMessagesfalseundefined
devtools.debugger.event-listener-breakpoints[]undefined
devtools.debugger.event-listeners-visiblefalsetrue
devtools.debugger.features.event-listeners-breakpointsfalsetrue
devtools.debugger.prefs-schema-version1.0.91.0.10
devtools.markup.mutationBreakpoints.enabledundefinedfalse
devtools.netmonitor.columnsData[{"name":"status","minWidth":30,"width":5}, {"name":"method","minWidth":30,"width":5}, {"name":"domain","minWidth":30,"width":10}, {"name":"file","minWidth":30,"width":25}, {"name":"cause","minWidth":30,"width":10},{"name":"type","minWidth":30,"width":5},{"name":"transferred","minWidth":30,"width":10},{"name":"contentSize","minWidth":30,"width":5},{"name":"waterfall","minWidth":150,"width":25}][{"name":"status","minWidth":30,"width":5}, {"name":"method","minWidth":30,"width":5}, {"name":"domain","minWidth":30,"width":10}, {"name":"file","minWidth":30,"width":25}, {"name":"url","minWidth":30,"width":25}, {"name":"cause","minWidth":30,"width":10},{"name":"type","minWidth":30,"width":5},{"name":"transferred","minWidth":30,"width":10},{"name":"contentSize","minWidth":30,"width":5},{"name":"waterfall","minWidth":150,"width":25}]
devtools.netmonitor.features.webSocketsundefinedfalse
devtools.netmonitor.ws.payload-preview-heightundefined450
devtools.netmonitor.ws.payload-preview-widthundefined550
devtools.responsive.viewport.angleundefined0
devtools.webconsole.features.editorundefinedfalse
devtools.webconsole.groupWarningMessagesfalsetrue
dom.IntersectionObserver.enabledtrueundefined
dom.battery.enabledtrueundefined
dom.beforeunload_timeout_msundefined1000
dom.dialog_element.enabledfalseundefined
dom.events.asyncClipboardtrueundefined
dom.events.asyncClipboard.dataTransferfalseundefined
dom.forms.datetimetrueundefined
dom.forms.inputmodefalseundefined
dom.gamepad.enabledtrueundefined
dom.gamepad.extensions.enabledtrueundefined
dom.gamepad.haptic_feedback.enabledtrueundefined
dom.gamepad.non_standard_events.enabledfalseundefined
dom.gamepad.test.enabledfalseundefined
dom.imagecapture.enabledfalseundefined
dom.input.dirpickerfalseundefined
dom.inputevent.data.enabledtrueundefined
dom.inputevent.inputtype.enabledtrueundefined
dom.ipc.keepProcessesAlive.privileged1undefined
dom.ipc.keepProcessesAlive.privilegedaboutundefined1
dom.ipc.processCount.privileged1undefined
dom.ipc.processCount.privilegedaboutundefined1
dom.ipc.processCount.privilegedmozillaundefined1
dom.ipc.processCount.webIsolatedundefined1
dom.manifest.onappinstalledfalseundefined
dom.media.autoplay.autoplay-policy-apifalseundefined
dom.moduleScripts.enabledtrueundefined
dom.performance.time_to_contentful_paint.enabledfalseundefined
dom.performance.time_to_dom_content_flushed.enabledfalseundefined
dom.performance.time_to_first_interactive.enabledfalseundefined
dom.performance.time_to_non_blank_paint.enabledfalseundefined
dom.permissions.revoke.enablefalseundefined
dom.pointer-lock.enabledtrueundefined
dom.presentation.controller.enabledfalseundefined
dom.presentation.enabledfalseundefined
dom.presentation.receiver.enabledfalseundefined
dom.registerContentHandler.enabledfalseundefined
dom.select_events.enabledtrueundefined
dom.sidebar.enabledtrueundefined
dom.storage.next_genfalsetrue
dom.storage.testingfalseundefined
dom.udpsocket.enabledfalseundefined
dom.visualviewport.enabledfalseundefined
dom.vr.enabledfalseundefined
dom.vr.external.enabledfalseundefined
dom.vr.oculus.enabledtrueundefined
dom.vr.oculus.quit.timeout10000undefined
dom.vr.openvr.action_inputtrueundefined
dom.vr.openvr.enabledfalseundefined
dom.vr.osvr.enabledfalseundefined
dom.vr.process.enabledfalseundefined
dom.vr.puppet.submitframe0undefined
dom.vr.service.enabledtrueundefined
dom.vr.test.enabledfalseundefined
dom.w3c_pointer_events.enabledtrueundefined
dom.webaudio.enabledtrueundefined
dom.webdriver.enabledtrueundefined
dom.webgpu.enablefalseundefined
dom.webkitBlink.filesystem.enabledtrueundefined
dom.webmidi.enabledfalseundefined
dom.window.event.enabledtrueundefined
extensions.webcompat-reporter.enabledfalsetrue
geo.enabledtrueundefined
geo.wifi.urihttps://www.googleapis.com/geolocation/v1/geolocate?key=%GOOGLE_LOCATION_SERVICE_API_KEY%https://location.services.mozilla.com/v1/geolocate?key=%MOZILLA_API_KEY%
gfx.downloadable_fonts.woff2.enabledtrueundefined
gfx.logging.peak-texture-usage.enabledfalseundefined
gfx.logging.slow-frames.enabledfalseundefined
gfx.logging.texture-usage.enabledfalseundefined
gfx.text.disable-aafalseundefined
gfx.webrender.allfalseundefined
gfx.webrender.blob.invalidationtrueundefined
gfx.webrender.enabledfalseundefined
gfx.webrender.force-disabledfalseundefined
gfx.webrender.split-render-rootsfalseundefined
gfx.work-around-driver-bugstrueundefined
gl.msaa-level2undefined
image.animated.decode-on-demand.recycletrueundefined
image.cache.size5242880undefined
image.cache.timeweight500undefined
image.mem.animated.discardabletrueundefined
image.mem.decode_bytes_at_a_time16384undefined
image.mem.surfacecache.discard_factor1undefined
image.mem.surfacecache.max_size_kb1048576undefined
image.mem.surfacecache.min_expiration_ms60000undefined
image.mem.surfacecache.size_factor4undefined
image.multithreaded_decoding.idle_timeout600000undefined
image.multithreaded_decoding.limit-1undefined
javascript.options.experimental.await_fixfalseundefined
javascript.options.experimental.fieldsfalseundefined
layers.acceleration.disabledfalseundefined
layers.acceleration.force-enabledfalseundefined
layers.amd-switchable-gfx.enabledtrueundefined
layers.async-pan-zoom.enabledtrueundefined
layers.bufferrotation.enabledtrueundefined
layers.componentalpha.enabledtrueundefined
layers.enable-tilesfalseundefined
layers.enable-tiles-if-skia-pomtpfalseundefined
layers.omtp.paint-workers-1undefined
layers.tile-height512undefined
layers.tile-width512undefined
layers.tiles.adjusttrueundefined
layout.css.DOMMatrix.enabledtrueundefined
layout.css.DOMPoint.enabledtrueundefined
layout.css.DOMQuad.enabledtrueundefined
layout.css.convertFromNode.enabledfalseundefined
layout.css.font-loading-api.enabledtrueundefined
layout.css.individual-transform.enabledfalseundefined
layout.css.initial-letter.enabledfalseundefined
layout.css.motion-path.enabledfalseundefined
layout.css.osx-font-smoothing.enabledfalseundefined
layout.css.overflow-clip-box.enabledfalseundefined
layout.css.overscroll-behavior.enabledtrueundefined
layout.css.prefixes.animationstrueundefined
layout.css.prefixes.border-imagetrueundefined
layout.css.prefixes.box-sizingtrueundefined
layout.css.prefixes.font-featurestrueundefined
layout.css.prefixes.transformstrueundefined
layout.css.prefixes.transitionstrueundefined
layout.css.scrollbar-color.enabledtrueundefined
layout.css.scrollbar-width.enabledtrueundefined
layout.css.text-justify.enabledtrueundefined
layout.css.touch_action.enabledtrueundefined
layout.display-list.retain.chromefalsetrue
media.allowed-to-play.enabledfalseundefined
media.autoplay.allow-mutedtrueundefined
media.eme.hdcp-policy-check.enabledfalseundefined
media.eme.vp9-in-mp4.enabledfalseundefined
media.hardware-video-decoding.force-enabledfalseundefined
media.ondevicechange.enabledtrueundefined
media.peerconnection.dtmf.enabledtrueundefined
media.peerconnection.identity.enabledtrueundefined
media.peerconnection.rtpsourcesapi.enabledtrueundefined
media.seekToNextFrame.enabledtrueundefined
media.setsinkid.enabledfalseundefined
media.track.enabledfalseundefined
media.videocontrols.picture-in-picture.video-toggle.always-showundefinedfalse
media.webaudio.audiocontextoptions-samplerate.enabledtrueundefined
media.webvtt.debug.loggingundefinedfalse
media.webvtt.regions.enabledtrueundefined
network.cookie.cookieBehaviorundefined4
network.cookie.thirdparty.nonsecureSessionOnlyfalseundefined
network.cookie.thirdparty.sessionOnlyfalseundefined
network.http.spdy.bug1556491trueundefined
network.http.spdy.bug1562315trueundefined
network.http.spdy.bug1563695trueundefined
network.trr.skip-AAAA-when-not-supportedundefinedtrue
network.trr.wait-for-A-and-AAAAundefinedtrue
network.warnOnAboutNetworkingtruefalse
permissions.desktop-notification.postPrompt.enabledfalsetrue
plugins.click_to_playtrueundefined
prio.publicKeyA35AC1C7576C7C6EDD7FED6BCFC337B34D48CB4EE45C86BEEFB40BD8875707733undefined
prio.publicKeyB26E6674E65425B823F1F1D5F96E3BB3EF9E406EC7FBA7DEF8B08A35DD135AF50undefined
privacy.trackingprotection.cryptomining.enabledundefinedtrue
privacy.trackingprotection.fingerprinting.enabledundefinedtrue
security.disallow_non_local_systemprincipal_in_testsundefinedfalse
security.identitypopup.recordEventElemetrytrueundefined
security.identitypopup.recordEventTelemetryundefinedtrue
security.remote_settings.intermediates.parallel_downloadsundefined8
security.webauth.u2ftrueundefined
security.webauth.webauthntrueundefined
services.sync.engine.bookmarks.bufferfalsetrue
services.sync.engine.bookmarks.validation.enabledundefinedtrue
services.sync.engine.passwords.validation.enabledundefinedtrue
services.sync.prefs.sync.app.shield.optoutstudies.enabledundefinedtrue
services.sync.prefs.sync.browser.discovery.enabledundefinedtrue
services.sync.prefs.sync.browser.newtabpage.activity-stream.showSponsoredundefinedtrue
services.sync.prefs.sync.browser.search.widget.inNavBarundefinedtrue
services.sync.prefs.sync.browser.sessionstore.restore_on_demandtrueundefined
signon.generation.availableundefinedfalse
signon.generation.enabledundefinedfalse
signon.includeOtherSubdomainsInLookupundefinedfalse
signon.management.page.faqURLundefinedhttps://lockwise.firefox.com/faq.html
signon.management.page.feedbackURLundefinedhttps://www.surveygizmo.com/s3/5036102/Lockwise-feedback?ver=%VERSION%
slider.snapMultiplier0undefined
svg.transform-box.enabledtrueundefined
urlclassifier.blockedTabletest-block-simple,mozplugin-block-digest256moztest-block-simple,mozplugin-block-digest256
urlclassifier.malwareTablegoog-malware-proto,goog-unwanted-proto,test-harmful-simple,test-malware-simple,test-unwanted-simplegoog-malware-proto,goog-unwanted-proto,moztest-harmful-simple,moztest-malware-simple,moztest-unwanted-simple
urlclassifier.phishTablegoog-phish-proto,test-phish-simplegoog-phish-proto,moztest-phish-simple
urlclassifier.trackingAnnotationTabletest-track-simple,ads-track-digest256,social-track-digest256,analytics-track-digest256,content-track-digest256moztest-track-simple,ads-track-digest256,social-track-digest256,analytics-track-digest256,content-track-digest256
urlclassifier.trackingAnnotationWhitelistTabletest-trackwhite-simple,mozstd-trackwhite-digest256moztest-trackwhite-simple,mozstd-trackwhite-digest256
urlclassifier.trackingTabletest-track-simple,base-track-digest256moztest-track-simple,base-track-digest256
urlclassifier.trackingWhitelistTabletest-trackwhite-simple,mozstd-trackwhite-digest256moztest-trackwhite-simple,mozstd-trackwhite-digest256
webgl.enable-webgl2trueundefined
widget.wayland_dmabuf_backend.enabledundefinedfalse
Default pref Javascript files
PrefFirefox 68.0.1Firefox 69.0 beta 6
browser/omni.ja.d/defaults/preferences/debugger.jspresentpresent
browser/omni.ja.d/defaults/preferences/devtools-client.jspresentpresent
browser/omni.ja.d/defaults/preferences/devtools-startup.jspresentpresent
browser/omni.ja.d/defaults/preferences/firefox-branding.jspresentpresent
browser/omni.ja.d/defaults/preferences/firefox-l10n.jspresentpresent
browser/omni.ja.d/defaults/preferences/firefox.jspresentpresent
browser/omni.ja.d/defaults/preferences/webide.jspresentpresent
omni.ja.d/defaults/pref/marionette.jspresentpresent
omni.ja.d/defaults/pref/remote.jsundefinedpresent
omni.ja.d/defaults/pref/services-sync.jspresentpresent
omni.ja.d/greprefs.jspresentpresent