I am sharing these post that why exchanges provide different rates in all coins. 
Exchanges
All Exchanges Take charge of your mind or say that it takes the exchanges to explain the amount of the actual amount. It will be as long as the crypto does not come in the currency context. The owner of the exchange is making a lot of money from his own interest and it will not be a crypto currency legal until it is ready to be made. Today, the rate of bitcoin is around $ 6,700, does anyone know what the actual price of bitcoin is.... can anyone tell me what actual price is bitcoin .
First opinion It is spread. Spread is the profit margin that every exchange charge being trading Second opinion is Price is determined by supply and demand and since each exchange has a different number of users all looking to buy and sell at different times, the prices can vary across exchanges. If you have multiple accounts across different exchanges you can profit from this spread just like many hedge funds are starting to do. Cryptocurrency Arbitrage explains how this is done to generate a profit.
The only reason is profit margin. As there no central regulatory authority governing crypto trading or exchanges, exchanges do their monopoly. Every exchange have their pros and cons. And only to gain the profit the price differences across exchanges i.e. Zebpay, Hitbtc, Binance , coinbase, koinex etc.
Hope this is helpful. One should consider the following factors while trading:
Trading Fees : Buy, Sell, Transfer
Speed of order execution
Hopefully this is helpful. I know crypto is not preferred by government, but this is my personal opinion.