They will provide a method of trading allowing to make profit on difference in crypto currency rates. But I dont understand how it works. Isnt it just margin trading?
No, the principle is little bit different. It will be possible to make profit on difference in rates on various exchanges. For example, Ethereum costs $120 on exchange A, and $119 on exchange B. It will be possible to buy it on exchange B and sell it on exchange A, earning a dollar.