Lemmy is Reddit.
Mastadon is Twitter.
Kbin is a bit of both.
They federate. So imagine using your Reddit account to reply to a tweet. And vice versa.
They don’t share the same servers - they just communicate with each other. Kind of like how I can use Gmail to write to a friend that uses a Yahoo Mail.
Here is a list of Apps coming to Lemmy:
https://kbin.social/m/kbinMeta/t/71764
Plenty for iOS to chose from, Christian’s legacy continues. Memmy and Mlem both feel pretty close to Apollo - and are both directly inspired by it.
These apps are in early beta. They have constant updates (daily for Memmy and weekly for Mlem), so you can kind of see them being built in real time. If you’re patient with the developers, you’ll get that Apollo experience very soon. It’s like 80% of the way there.
Liftoff is pretty cool too, though it’s a different design approach.
(I’m using Memmy now, actually.)