I always think it's funny to see Hubzilla devs say that "Hubzilla is not a social network". It's true that it does many other things than contemporary social networking, but the components that it provides for posts, streams, and messaging are actually very good. To some certain extent it's actually better than most self-described social networks.
In a nutshell, Hubzilla is a combination of the following things:
- Cloud Storage (comparable to OwnCloud)
- Content Management System (comparable to Drupal)
- Federated Communications Platform (comparable to Friendica)
- Community Social Platform (comparable to Ning)
- Remote Identity Management with Authentication (comparable to Mozilla Persona)
- Publishing & Syndication System (comparable to WordPress)
- Personal Information Manager (comparable to some parts of Kontact)
And the funny thing is that it does all of this quite well. It also offers a robust extension system that can add all sorts of new functionality (such as maps, chess games, and even a wiki).