This is difference between the default preference of Firefox 62.0 beta 6 and one of 61.0.1.

Preference difference
PrefFirefox 61.0.1Firefox 62.0 beta 6
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.android.chrome_fling_physics.enabledfalsetrue
browser.EULA.version3undefined
browser.cache.disk.max_chunks_memory_usage1024040960
browser.cache.disk.max_priority_chunks_memory_usage1024040960
browser.cache.offline.insecure.enabletruefalse
browser.history_swipe_animation.disabledundefinedfalse
browser.rights.3.shownfalseundefined
browser.rights.version3undefined
browser.safebrowsing.provider.mozilla.lists.baseundefinedmoz-std
browser.safebrowsing.provider.mozilla.lists.base.descriptionmozstdDescundefined
browser.safebrowsing.provider.mozilla.lists.base.namemozstdNameundefined
browser.safebrowsing.provider.mozilla.lists.contentundefinedmoz-full
browser.safebrowsing.provider.mozilla.lists.content.descriptionmozfullDesc2undefined
browser.safebrowsing.provider.mozilla.lists.content.namemozfullNameundefined
browser.search.defaultenginenamechrome://browser-region/locale/region.propertiesundefined
browser.search.defaultenginename.USdata:text/plain,browser.search.defaultenginename.US=Googleundefined
browser.search.order.1chrome://browser-region/locale/region.propertiesundefined
browser.search.order.2chrome://browser-region/locale/region.propertiesundefined
browser.search.order.3chrome://browser-region/locale/region.propertiesundefined
browser.search.order.US.1data:text/plain,browser.search.order.US.1=Googleundefined
browser.search.order.US.2data:text/plain,browser.search.order.US.2=Bingundefined
browser.security.newcerterrorpage.enabledundefinedfalse
browser.sessionstore.resuming_after_os_restartundefinedfalse
browser.snapshots.limit0undefined
browser.tabs.multiselectundefinedfalse
browser.tabs.remote.tabCacheSizeundefined0
browser.urlbar.autoFill.typedtrueundefined
device.sensors.ambientLight.enabledtruefalse
device.sensors.proximity.enabledtruefalse
devtools.debugger.ignore-caught-exceptionsfalsetrue
devtools.debugger.pause-on-caught-exceptionsundefinedtrue
devtools.devedition.promo.enabledfalseundefined
devtools.devedition.promo.shownfalseundefined
devtools.devedition.promo.urlhttps://www.mozilla.org/firefox/developer/?utm_source=firefox-dev-tools&utm_medium=firefox-browser&utm_content=betadoorhangerundefined
devtools.inspector.fonthighlighter.enabledundefinedfalse
devtools.inspector.show-three-pane-tooltipfalsetrue
devtools.inspector.three-pane-enabledfalsetrue
devtools.inspector.three-pane-first-runundefinedtrue
devtools.inspector.three-pane-togglefalseundefined
devtools.new-animationinspector.enabledfalsetrue
devtools.telemetry.tools.opened.version{}undefined
devtools.toolbar.enabledtrueundefined
devtools.toolbar.visiblefalseundefined
devtools.toolbox.previousHostsideright
devtools.webconsole.autoMultilinetrueundefined
devtools.webconsole.jsterm.codeMirrorundefinedfalse
dom.keyboardevent.dispatch_during_compositionfalsetrue
dom.registerContentHandler.enabledtruefalse
dom.registerProtocolHandler.insecure.enabledtruefalse
extensions.geckoProfiler.getSymbolRuleslocalBreakpad,remoteBreakpad,nmlocalBreakpad,nm
extensions.geckoProfiler.symbols.urlhttp://symbols.mozilla.org/undefined
extensions.minCompatibleAppVersion4.0undefined
extensions.minCompatiblePlatformVersion2.0undefined
extensions.pocket.oAuthConsumerKeyundefined40249-e88c401e1b1f2242d9e441c4
extensions.systemAddon.update.enabledundefinedtrue
extensions.webextensions.ExtensionStorageIDB.enabledundefinedfalse
geo.provider.use_gpsdfalseundefined
geo.wifi.urihttps://www.googleapis.com/geolocation/v1/geolocate?key=%GOOGLE_API_KEY%https://location.services.mozilla.com/v1/geolocate?key=%MOZILLA_API_KEY%
gfx.webrender.allfalseundefined
gfx.webrender.async-scene-build2true
gfx.webrender.debug.echo-driver-messagesundefinedfalse
gfx.webrender.debug.new-frame-indicatorundefinedfalse
gfx.webrender.debug.new-scene-indicatorundefinedfalse
gfx.webrender.enabledfalseundefined
gfx.webrender.hit-testtrueundefined
hangmonitor.timeout0undefined
image.animated.decode-on-demand.threshold-kb419430320480
image.animated.resume-from-last-displayedundefinedtrue
image.mem.max_decoded_image_kb256000undefined
io.activity.intervalMillisecondsundefined0
javascript.options.array_prototype_valuestrueundefined
layout.accessiblecaret.allow_script_change_updatesfalseundefined
layout.accessiblecaret.script_change_update_modeundefined0
layout.css.getPropertyCSSValue.enabledfalseundefined
layout.css.scrollbar-colors.enabledundefinedfalse
layout.css.shape-outside.enabledfalsetrue
layout.css.text-combine-upright-digits.enabledfalseundefined
layout.css.webkit-appearance.enabledundefinedfalse
layout.display-list.retainfalsetrue
layout.event-regions.enabledfalseundefined
network.activity.intervalMilliseconds0undefined
network.cookie.maxNumberundefined3000
network.cookie.maxPerHostundefined180
network.dir.format2undefined
network.sts.poll_busy_wait_periodundefined50
network.sts.poll_busy_wait_period_timeoutundefined7
network.sts.pollable_event_timeoutundefined6
network.trr.blacklist-duration120060
plugin.java.mimeapplication/x-java-vmundefined
plugin.state.java1undefined
print.font-variations-as-pathsundefinedtrue
security.OCSP.GET.enabledfalseundefined
security.allow_chrome_frames_inside_contentfalseundefined
security.pki.name_matching_mode13
services.blocklist.addons.signerundefinedremote-settings.content-signature.mozilla.org
services.blocklist.gfx.signerundefinedremote-settings.content-signature.mozilla.org
services.blocklist.onecrl.signerundefinedonecrl.content-signature.mozilla.org
services.blocklist.pinning.signerundefinedpinning-preload.content-signature.mozilla.org
services.blocklist.plugins.signerundefinedremote-settings.content-signature.mozilla.org
services.sync.engine.bookmarks.validation.enabledundefinedtrue
services.sync.engine.passwords.validation.enabledundefinedtrue
startup.homepage_welcome_urlhttps://www.mozilla.org/%LOCALE%/firefox/%VERSION%/firstrun/about:welcome
Default pref Javascript files
PrefFirefox 61.0.1Firefox 62.0 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/services-sync.jspresentpresent
omni.ja.d/greprefs.jspresentpresent