There isn't really a relationship. They are just different markets to trade on. All markets should even out after time as markets that have lower BTC prices will see increased demand, while higher prices might see a reduction until parity.
Supply/Demand will cause all markets to remain constant. There really isn't any barriers minus the ability to fund/withdraw from them.
Thanks. And why some traders decide to buy/sell according to the price on BTC China ( the biggest market of BTC ) ? thanks