Different banks use different rates to attract their customers. Usually, smaller and unwell-know banks have higher rates; oppositely, the bigger and well-know banks have a little bit lower rates. As most investors believe that most well-know and big banks are rarely bankrupt. They believe these banks are too big to be failed. Therefore, investing in the big and well-know banks’ negotiable CD has less risks than investing in those small and unwell-know banks’ negotiable CD. Although small and unwell-know banks have a higher CD rates, investor should know that the higher rate is, the higher risk will be. So, investors should not just automatically choose the highest rate in negotiable CD.

首先你要了解 买入价和卖出价

是以站在银行的角度 买入价 就是银行买入该外汇品种的价格（也就是你卖给银行的价格）

卖出价 就是银行卖出该外汇品种的价格（也就是你向银行买的价格）

一般银行和外汇交易机构 可以通过 买入和卖出的这个点差获得一定的利益

你说的汇率不同大概就是这个差价银行与银行之间的不同 吧