We have "Episodes" which are gmed events. Like episode one, for example, had two characters kidnapped by a mob boss, which ended up with the crew shooting the mob thugs off the ship before taking off. Between episodes, it's sandbox-style, meaning that characters can RP their things together, bond and form relationship (friends, lovers, enemies, etc.).
Fandomverse is a larger group, but the Firefly-based ship is always ion its own, travelling in Firefly-based universe, and will most likely never interact with the other characters.
I hope that helps. :)