主要区别在于：1.在关系副词引导的定语从句中,由于引导词的副词属性,只能作状语.That is the room where your parents had lived.where 地点状语。I still remember that day when I first came to Shanghai fifty years ago.when 时间状语。2.在关系代词引导的定语从句中,引导词可以作主语和宾语、定语(状语当然不能作)。This is the man who tells me the mews who 主语。The man whom you want to see is in the office.whom 不定式to see 的宾语 。Is it you who knock at the door.who 主语。Do you recognize the man whose hat is black.whose 定语。Here is the book which the teacher mentioned yesterday.which 宾语。This is the power station that(which)the peasants built last year.that 宾语。