Piefed has quite a few features that Lemmy doesn’t have:

• multicommunities
• onboarding process asking new joiners what they are into
• crossposts comments consolidation
• communities moderation features
• posts and user flairs
• keyword filters

https://join.piefed.social/features/

Lemmy should get there in version 1.0, but they still don’t have any precise timeframe for that release, and still need to do some testing https://lemmy.ml/comment/23570258