Pretty much the last word on BuddyPress vs bbPress:
BuddyPress and bbPress are not connected.
BuddyPress allows you to install a forked version of bbPress. It is not the same as this bbPress. We don’t know why they kept the name. We don’t know why they don’t publicise that they are different. […]
If what you need is a forum, use bbPress.
If you need to build a social network (friends, groups, private messaging, activity) then use BuddyPress.
Thats basically it 🙂