My question is why is the rate higher on one exchange than on another?
The trading volume on each exchange is different. and it is also influenced by demand and supply in a particular exchange.
Maybe you have heard of traders using arbitrage. they take advantage of the price difference from certain exchanges to make a profit.
This arbitrage trading situation makes it possible that there will be the same price adjustment in a short time on each exchange. I don't think the price difference that occurs on each exchange is too big. the moment may happen very quickly when pump and dump.