which和what引导从句的区别是本身的意义不同。which的意思是哪一个，后面还要接名词，what翻译成什么，which和what在宾语从句中同属连接代词，在从句中可做主语、宾语及定语。

例句：You must signal which way you are going to turn.你要朝哪个方向转，必须发出信号。There are two points which I wanted to make.我想要指出的有两点。What made you choose the one rather than the other?你怎么选了这个而不是那个？