What's the difference between 集中 and 专心 Both of them refer to "to focus on" or "to concentrate". 

I know that if you want to specifically refer to something inanimate being concentrated in something, then you would use 集中, ex. 酒吧集中在那个地方. 

However, other than that, it seems like you can use the two interchangeably when referring to a person concentrating in something. 

Thank you for any help.
專心 is a state of mind, roughly "concentrate, focus one's attention"

集中 is "gather or bring together", roughly "summon, muster"