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.

关系词的选择依据在从句中所作的成分,先行词在从句中作主、定、宾语时,选择关系代词（who,whom,that,which,whose）；先行词在从句中做状语时,应选择关