Hmmm... Do you mean PBeM or pen & paper ones? In my experience, they tend to work a bit differently, but do have major similarities.
The PBeM one I'm in (click sig banner for details :P ) has everyone working together to basically play out the lives of their characters, which includes the various scrapes they and their ship get into.
Pen & paper... In my experience (both playing and running), this type tends to focus more on the action and adventure side of things, though players often still manage to work in their character's lives "off-stage" into things anyway :)
Hope this is even remotely helpful, but if there's anything else you want, feel free to poke me and I'll see if I can come up with a better explanation :)