@MarcusAnthonyCyganiak yes, the entire network is Fediverse and Mastodon is only a part of it, albeit a huge one, they didnt, and still aren't, earning a very good reputation for being an overall positive part of the Fediverse.
That's a whole different beast of an issue though.
Overall, Fediverse has MANY different softwares, as it is the nickname for softwares that use the ActivityPub protocol to communicate.
If you'd like to know more about the platforms and their specific use cases, I'd suggest reading the "Software using ActivityPub" section on the Wikipedia page.
https://en.m.wikipedia.org/wiki/ActivityPub
The list isn't complete, as their is new software all the time, and some softwares on the list are no longer updated, but it's a decent start.