Lemmy and Kbin are actually completely different apps, like Lemmy and Mastadon, but they can federate with each other through the Activity Pub protocol, and they both happen to be aiming to be Reddit replacements. (Kbin is also aiming to have some Twitter-like functionality as well.) I like the way Kbin sorts its posts better, but I like Lemmy’s terminology more. I don’t mind either of their UI.