@leroy It's a separate platform using ActivityPub and can communicate with Mastodon, etc.
It's modular. Devs can create plug-ins to add features. For example, you can run different "apps", including social (Mastodon-like), community (Forum-like) while using the same core components but different feature sets.
The social app is the first release candidate, with a unique feature of boundaries, your posts can be shared to specific people within your "circles".