The top level tabs have roughly stayed the same while the visual style has been tweaked to be cleaner and the owl has been redrawn.

The Clubs feature is being A/B tested against the Leaderboards tab (and some users aren't happy about it: Petition to save Clubs)

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Duolingo

Onboarding
Top level tabs
Learning experience
Gamification: Badges
App Store screenshots
Change or add language
Duolingo Plus
Duolingo Clubs
App icon change
Create profile
Asking for notiification permissions during onboarding
Gamification memes
Gamification: Streak, Lives and Gems

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Content Screens

Discover tab
Top level tabs
Restaurant page
Top level tabs