the woman is an actress. she is very pretty.
이면요..who를 사용하면 the woman who is very pretty is an actress.
답인데...
다른 것들을 보면 a microwave is a machine. it heats food.
a microwave is a machine which heats food.
이런데..

둘이 무슨 차이가 있는 거예요??