Lemmy has been around longer, so it is probably more robust, but Kbin has more features, including the ability to follow individual users across the 'verse, and has support for a number of Fedi groups, including Friendica Forums and Guppe Groups, that Lemmy has no support for.
They're both Reddit-esque Fediverse platforms, but are developed and maintained by different people.
I thought kbin was more like Mastodon, but maybe I'm confusing it with something else.
Huh, maybe I'll look into it
Lemmy has been around longer, so it is probably more robust, but Kbin has more features, including the ability to follow individual users across the 'verse, and has support for a number of Fedi groups, including Friendica Forums and Guppe Groups, that Lemmy has no support for.