Lemmy is like Reddit for the fediverse. Mastodon is like Twitter for the fediverse. there's a version of facebook for the fediverse, instagram for the fediverse, etc.
the fediverse is better in that it's designed to be non-corporate and open-source and other good things
in theory, you should be able to post from one part of the fediverse to the other
someone was like: here's a proof of concept that you can post from one part of the fediverse to ALL the other parts of the fediverse!
a mod was like: your post is pointless and an annoyance and you are just working for advertisers
the poster was like: wat? how would advertising work?
the mod was like: give me money or leave me alone, and then locked and removed the post.