关系代词有who,whom,that,which,whose,关系副词有where(地点）,when（时间）,why（原因）.
总体来说关系副词在定语从句中做状语
他们和关系代词主要的区别是where,when,why=介词+which
eg:This is the house in which (where) I lived last year.
This is the reason for which (why) he was late for school.
That's the day on which (when) I met him in the street.