Quote Originally Posted by Darobat
What are some cases where you could use вместе but not сообща?
sorry my prev post must have been rather confusing

мы были вместе is ok

мы были сообща - is weird(although it could probably be used meaning that they were in a tight spot but were actively helping each other out)

сообща sort of has the same root as сообщаться so rougly сообща translates as in cooperation with each other, thus мы сделали это сообща means we did it in cooperation with each other. In russian this word has become an idiom - сообща and is now only used for actions as an adverb and is never used for states, only for actions done by people (closely) cooperating with each other. Obviosly together can be synonimous in this meaning so that we did it together and we did it in cooperation with each other both mean pretty much the same thing. Yet to be together with somebody is a different story, you don't have to be doing anything