/kbin magazines, Lemmy communities and Friendica forums are (according to ActivityStreams vocabulary) groups. However, the same applies to Mobilizon groups, which work slightly differently, allow private discussions, having common file resources, and most important of all - organising events.
We could also call these three subfeddits, which is another word to learn ;)
or simply to go ahead. All communities and forums already will be seen by /kbin as magazines, and the same is accordingly true to other software.

Also, not all vocabulary aligning is actually desired - /kbin explicitly uses name boost to align with Mastodon feature. However, both "boost" and upvote have a "boosting" effect - the meaning of the feature (being simply reblog or re-tweet) is obscured right now.

Another confusing Mastodon nomenclature alignement is calling only microblog posts posts. Majority of /kbin users are Reddit emigrants right now, and Reddit used name post for /kbin article. In reality, everything, from articles and "tweets", through audio and video, to places, events and relationships (!), can in ActivityPub be called posts. ActivityStreams vocabulary differentiates between an article (long form, formatted), and note (short, equivalent of tweet and toot), and IMO /kbin should adopt the name note for microblog posts - to reduce confusion (Calc- and Misskey already use that name).