互相： each other 一起： together so 一起学习 means study together 互相学习 means I have something that you can study and you have something that I can study.

I thought the same...together=一起/一同/在一起 Then I checked the dict. "together" has a synonyms, mutually. Back to your question, you mentioned "study together", is it "two people"? It would explain.If two people study together, then it could be that "they learn from each other"^^ The common translation for 互相 would be "mutual, each other", "together" is seldom used, except the above-mentioned case, it refers to "two people/sides/parties" http://www.wordreference.com/enzh/together

I think you are right. 'together' is 在一起 and that 互相 is 'each other'. The translator must make a mistake. For exmaple, 他们一起学习中文。They learn Chinese together. 相互学习 is “learn from each other” 我们得相互学习。We should learn from each other. 相互 also means "mutual" mutual understanding=相互理解 mutual coorperation =相互合作

it depends on the context. i can't tell you from this.