in addition to 和 except for

except for 除了...以外（与 except for 连用的整体词与 except for 所跟的词往往不是同类的，是指整体中除去 一个细节。） 

eg：Your composition is good except for a few spelling mistakes.   
     除了几处拼写错误以外， 你的作文写得很好。 


in addition to除...之外(还)【及物】 

eg：In addition to French, he has to study Japanese. 
    除了法语外,他还得学日语。