구별하다

tell, classify, distinguish

You look very very much alike. 둘이 너무 똑같이 생겼는데
And how do people tell you apart ? 사람들은 어떻게 너희를 구분하니?

to tell sb/sth apart
to distinguish between

[출처] (쌍둥이처럼) 비슷한 것의 차이점을 구별하다 – http://blog.naver.com/wkd10042000/90195543390