Well that's three, there are at least 1200 more and that's not including the YouTube and Instagram like sites that are, or could be, federated, and they all have slightly different feature sets depending on what software they're running.
That's what I'm talking about. A way to describe those feature sets in a word.
But the term you might be looking for is federated. Each platform has its own lexicon for what it stands for and how to interact. Is pictures, videos, content aggregation, microblogging, blogging, etc. there are more than 1200 and each has its own internal language and how users refer to it. No different than facebook, Twitter, instagram, blogger, blogspot, MySpace, …, etc. But, they all run on activitypub, which is an agreed upon format for things. The various forms are new and developing, so every form of social interaction is different in how they refer to themselves.
Yeah I get how it works but I have problems explaining it to someone without going on a rant and explaining activitypub. I suppose at this stage that's to be expected, before everyone knew what a website was someone had to tell people about http.
The fediverse (a portmanteau of "federation" and "universe") is an ensemble of federated (i.e. interconnected) servers that are used for web publishing (i.e. social networking, microblogging, blogging, or websites) and file hosting, which, while independently hosted, can communicate with each other.