As I've been told many times, there are no stupid questions.. and when it comes to prospective users, that's doubly true
To start, JomSocial's Facebook integration may be all you need, and we'd honestly recommend you start with it. It will let user's easily sign up to your site, but that's about where it ends. JFBConnect adds the ability to import the user's Facebook profile into JomSocial automatically, so that you can have their college, employer, favorite books or music, and other types of information so that you can get that information without additional forms for the user.
Additional features during registration are automatic username generation which means that JFBConnect will create the Joomla username for the user automatically so they don't see any forms during registration. Generally, this isn't as great for a 'social' site, but is great for an ecommerce site or other place where you just want user's to register immediately.
A little further along with registration and logging in, JFBConnect has the ability to post to the user's wall when they register or login with a link back to your site. This is great to automatically promote your site to your new user's friends.
Beyond registration, and into territory that JomSocial doesn't venture, we have all the social widgets including Like buttons, Comment widgets, Fan boxes, etc. These all help to tie your site into Facebook and get more cross-communication going, which again, helps promote your site by more posts to user's wall. Additionally, we fully support the Open Graph protocol which lets you (easily) describe your page to Facebook. Similar to standard meta tags, you can set the title, description, image and extra information about your page that will show up in a user's wall when posting there.
For easy-integration, we have a content plugin which can automatically insert the Like or Comment box into all your content/articles so you don't have to deal with it.
So, that's a lot of the 'big' features we have now. Our 4.0 release is coming up in July, which will have a handful of really nifty features we can't wait to start promoting, but not quite yet
Again, we'd recommend trying JomSocial's integration.. then, if you think it's not right for you, try JFBConnect. We even have the ability to import your existing Facebook/Joomla connections, so you won't loose anything when you do. We also have a 30-day money back guarantee, so no worries there.
For all the features (though still some things are missing), see our features page and click around a bit
www.sourcecoast.com/jfbconnect/features
Hope this all helps, and should you need anything else, let us know!
Alex