Lemmy

@naoseiquemsou
They are both using ActivityPub. ActivityPub is not a fixed protocol in itself but a framework for making protocols and implement any feature you want. So that means that some features available on some systems aren't compatible with others. For example Misskey and Pleroma (and forks such as Calckey and Akkoma) have emoji reactions which aren't compatible on other systems and therefore can't be seen. But the basic stuff such as follow, post, comment, like is compatible with all systems.

If you search for ActivityPub Fediverse software, you will find which systems you are able to interact with. Lemmy is a bit more limited than other systems because you can only see posts posted in a Lemmy community. You can't interact with for example a Mastodon posts if it isn't posted in a Lemmy community. However I found Kbin to be a good mix. Has the same features as Lemmy plus the Mastodon stuff: a profile for posts, boosts and can interact with any post on the whole Fediverse.