Too many people are confusing the two. Whenever lemmy.ml or its devs do something stupid, people go “Lemmy is getting worse and worse,” or “I’m leaving Lemmy,” or worse, “I’m leaving for Beehaw.”
If you’re using Beehaw, then you’re using Lemmy. Lemmy is the software these instances run on. If you don’t like lemmy.ml, join another instances that have rules that match your philosophy. Some instance hosts authoritarian or fascist shit? Turn to another Lemmy instance. Lemmy.ml is not even the biggest instance. People who just joined and are unfamiliar with the platform will just think the entire Lemmyverse is run by autocratic admins if we don’t get our terminology right.
Whoever has permission to merge into the main branch of the code repository would have final say. All pull requests for the lemmy repo are currently public though, so you’d be able to see an abuse of power if one were to happen. More users can also be granted the ability to merge code into the main branch as well, which more than likely will happen with the biggest contributors.