This is difference between the default preference of Firefox 83.0 beta 3 and one of 82.0. This diff table is generated with my small script firefox-prefjs-surveyer.

Preference difference
PrefFirefox 82.0Firefox 83.0 beta 3
app.releaseNotesURL https://www.mozilla.org/%LOCALE%/firefox/%VERSION%/releasenotes/?utm_source=firefox-browser&utm_medium=firefox-browser&utm_campaign=whatsnew https://www.mozilla.org/%LOCALE%/firefox/%VERSION%beta/releasenotes/?utm_source=firefox-browser&utm_medium=firefox-browser&utm_campaign=whatsnew
app.update.channel release beta
app.update.url.details https://www.mozilla.org/%LOCALE%/firefox/notes https://www.mozilla.org/%LOCALE%/firefox/beta/notes
app.update.url.manual https://www.mozilla.org/%LOCALE%/firefox/ https://www.mozilla.org/%LOCALE%/firefox/beta
apz.allow_zooming false true
apz.force_disable_desktop_zooming_scrollbars true false
apz.windows.use_direct_manipulation false true
browser.cache.offline.storage.enable true false
browser.contentblocking.report.hide_vpn_banner undefined false
browser.contentblocking.report.vpn-android.url undefined https://play.google.com/store/apps/details?id=org.mozilla.firefox.vpn&referrer=utm_source%3Dfirefox-browser%26utm_medium%3Dfirefox-browser%26utm_campaign%3Dabout-protections-mobile-vpn%26anid%3D--
browser.contentblocking.report.vpn-ios.url undefined https://apps.apple.com/us/app/firefox-private-network-vpn/id1489407738
browser.contentblocking.report.vpn-promo.url undefined https://vpn.mozilla.org/?utm_source=firefox-browser&utm_medium=firefox-browser&utm_campaign=about-protections-top-promo
browser.contentblocking.report.vpn.enabled undefined true
browser.contentblocking.report.vpn.url undefined https://vpn.mozilla.org/?utm_source=firefox-browser&utm_medium=firefox-browser&utm_campaign=about-protections-card
browser.contentblocking.report.vpn_platforms undefined win
browser.contentblocking.report.vpn_regions undefined us,ca,nz,sg,my,gb
browser.contentblocking.report.vpn_sub_id undefined sub_HrfCZF7VPHzZkA
browser.defaultbrowser.notificationbar false true
browser.migrate.showBookmarksToolbarAfterMigration false true
browser.newtabpage.activity-stream.showSponsoredTopSites undefined true
browser.newtabpage.activity-stream.telemetry.ut.events false true
browser.preferences.exposeHTTPSOnly false true
browser.toolbars.bookmarks.2h2020 undefined false
browser.urlbar.accessibility.tabToSearch.announceResults undefined true
browser.urlbar.update2 false true
browser.urlbar.update2.disableOneOffsHorizontalKeyNavigation false true
browser.urlbar.update2.localOneOffs false true
browser.urlbar.update2.oneOffsRefresh false true
browser.urlbar.update2.restyleBrowsingHistoryAsSearch undefined true
browser.urlbar.update2.tabToComplete false true
devtools.overflow.debugging.enabled false true
devtools.target-switching.enabled false true
doh-rollout.profileCreationThreshold 1572476400000 undefined
dom.compositionevent.text.dispatch_only_system_group_in_content true undefined
dom.datatransfer.mozAtAPIs false undefined
dom.forms.autocapitalize undefined false
dom.indexedDB.privateBrowsing.enabled undefined false
dom.input_events.beforeinput.enabled false true
dom.navigation.locationChangeRateLimit.count undefined 200
dom.navigation.locationChangeRateLimit.timespan undefined 10
dom.security.respect_document_nosniff true undefined
dom.storage.next_gen false true
dom.window.content.untrusted.enabled true false
extensions.webcompat-reporter.enabled false true
fission.autostart.session undefined false
fission.experiment.enrollmentStatus undefined 0
fission.experiment.startupEnrollmentStatus undefined 0
fission.openNonFissionWindowOption undefined false
fission.remoteObjectEmbed false true
geo.provider.network.compare.url undefined https://www.googleapis.com/geolocation/v1/geolocate?key=%GOOGLE_LOCATION_SERVICE_API_KEY%
geo.provider.network.url https://www.googleapis.com/geolocation/v1/geolocate?key=%GOOGLE_LOCATION_SERVICE_API_KEY% https://location.services.mozilla.com/v1/geolocate?key=%MOZILLA_API_KEY%
gfx.e10s.font-list.shared false true
gfx.font_loader.interval 50 undefined
gfx.webrender.max-partial-present-rects 0 1
gfx.webrender.picture-caching true undefined
gfx.webrender.picture-tile-height undefined 512
gfx.webrender.picture-tile-width undefined 1024
javascript.options.ion.threshold 1000 1500
javascript.options.warp undefined true
layers.gpu-process.crash-also-crashes-browser undefined false
layout.css.conic-gradient.enabled false true
layout.css.is-and-where-better-error-recovery.enabled false true
layout.css.math-depth.enabled undefined false
layout.css.math-style.enabled undefined false
layout.css.moz-any-is-is.enabled false true
layout.css.moz-touch-enabled.enabled false undefined
layout.dynamic-reflow-roots.enabled false true
mathml.deprecated_alignment_attributes.disabled false true
mathml.deprecated_menclose_notation_radical.disabled false true
mathml.deprecated_style_attributes.disabled false true
mathml.mathsize_names.disabled false true
mathml.mfrac_bevelled_attribute.disabled false true
mathml.mfrac_linethickness_names.disabled false true
mathml.script_shift_attributes.disabled false true
mathml.scriptminsize_attribute.disabled undefined false
mathml.scriptsizemultiplier_attribute.disabled undefined false
mathml.stixgeneral_operator_stretching.disabled false true
mathml.xlink.disabled false true
media.navigator.mediadatadecoder_vpx_enabled false true
media.peerconnection.dtls.version.min 770 771
media.peerconnection.mtransport_process false true
media.videocontrols.picture-in-picture.keyboard-controls.enabled false true
network.connectivity-service.DNSv4.domain mozilla.org example.org
network.connectivity-service.DNSv6.domain mozilla.org example.org
network.connectivity-service.nat64-check undefined true
network.dns.echconfig.enabled undefined false
network.dns.echconfig.fallback_to_origin_when_all_failed undefined true
network.dns.httpssvc.http3_fast_fallback_timeout undefined 50
network.dns.httpssvc.reset_exclustion_list undefined true
network.http.http3.enable_qlog undefined false
network.preload false true
network.process.enabled false true
network.trr.exclude-etc-hosts undefined true
network.trr.fallback-on-zero-response undefined false
pdfjs.renderInteractiveForms false true
permissions.isolateBy.privateBrowsing false true
print.printer_list undefined
print.tab_modal.enabled false true
privacy.annotate_channels.strict_list.enabled false true
privacy.partition.network_state false true
privacy.purge_trackers.enabled false true
privacy.purge_trackers.logging.level Error Warn
privacy.webrtc.globalMuteToggles undefined false
prompts.modalType.httpAuth 3 2
security.bad_cert_domain_error.url_fix_enabled false true
security.block_importScripts_with_wrong_mime true undefined
security.block_script_with_wrong_mime true undefined
security.csp.enableStrictDynamic true undefined
security.data_uri.unique_opaque_origin true undefined
security.disallow_non_local_systemprincipal_in_tests undefined false
security.intermediate_preloading_healer.enabled false true
security.pki.crlite_ct_merge_delay_seconds undefined 100800
security.remote_settings.crlite_filters.enabled false true
security.sri.enable true undefined
services.sync.engine.bookmarks.buffer true undefined
services.sync.engine.bookmarks.validation.enabled undefined true
services.sync.engine.passwords.validation.enabled undefined true
services.sync.prefs.sync.browser.newtabpage.activity-stream.showSponsoredTopSites undefined true
signon.recipes.path chrome://passwordmgr/content/recipes.json resource://app/defaults/settings/main/password-recipes.json
signon.recipes.remoteRecipesEnabled undefined true
toolkit.shutdown.lateWriteChecksStage 1 3
toolkit.telemetry.enabled false true
webgl.enable-surface-texture false true
webgl.out-of-process.force undefined false
widget.pause-compositor-when-minimized undefined true