My cousin just started as a Real estate brooker, he is the person between the seller and buyer of a house. 
brokers can be very useful I understand but I dont really understand their job
He tries to match up people who are selling their house and people who wants to buy a house. 
so a broker and agent are the same thing
Estate agent is the term used in the UK. 
oh I see, so really the term is interchangable depending on where you live?
There are also differences as for the obligation, liabilities  and powers between an estate agent in the UK and a real estate broker in the US.  
oh interesting but since I am in the US and not in the UK hopefully I wont be using one to buy in the UK anytime soon
ALso, in the US, real estate brokers are called listing broker or listing agents. They are all the same.
yes I am pretty sure I have heard them called all of those things