Of course there are difference between bank and cryptocurrency exchange. The main difference is bank exchange are centralised but cryptocurrency exchange are decentralised.
Why do you think that cryptocurrency exchanges are decentralized? Please take a look at larger exchanges like Bitfinex, Bitstamp or Kraken. None of them is decentralized, they hold your funds, you have no control what happens with your coins, you don't have any access to the private keys of "your" wallet hosted by the exchange.