The newest features I know of are a built in language auto translator, more fine tuned administrative controls geared towards specific members of other instance

The newest features I know of are a built in language auto translator, more fine tuned administrative controls geared towards specific members of other instances (something that's already fairly robust for both platforms), default instance wide progressive scrolling of large threads, support for editing posts. None of these are earth shattering, but all of them are very contentious aside from maybe the admin features. In general, Mastodon aims to maintain twitter feature parity, which is why things like the translator and are added. The ActivityPub protocol also doesn't really support the idea of an edit directly, and many see it as the latest in a long list of steps of mastodon trying to own the protocol. The progressive scroll / pagination vs load the whole thread thing is a constant front end argument within various mastodon/pleroma frontends and has been for years now. The problem is that unless you use one of the real minimal, 1337, hackerish frontends, threads with 300+ comments will send your RAM straight to frown town unless you have like 12gb to spare just for what is mostly static text.