1.词性就不同
quickly是副词,如果你要说"购买东西快"就说"Somebody buys things quickly"
prompt是形容词,副词是promptly
2.侧重点不同
quick指速度快,迅速
Good ware makes quick markets.
货好销得快.
Call and ask them to be quick.
打电话叫他们赶快.
She made a quick calculation.
她做了一次很快的计算.
prompt是偏重于反应快,意思是敏捷的,立刻的,立即的
Could you make prompt deliery?
可以即期交货吗?
She's always prompt to criticize other people's ideas.
她对别人想出的主意总是迫不及待地批评.
He is always prompt in answering letters.
他总是迅速回复来信.