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)

More screenshots from‏‏‎ ‎

Duolingo

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

More‏‏‎ ‎

Content Screens

Location page
Top level tabs
Top level tabs
Home tab