You're right. Head is 머리 and hair is 머리카락. But korean people call borh head and hair '머리'. haha so you should understand what '머리' means in the context people talk about. :) ex) 1.내 머리가 너무 길어, 머리 좀 잘라야 겠어. (My hair is too long, I need to cut my hair some.) 2. 그 생선을 요리하기 전에, 생선 머리를 자르세요. (Before cooking the fish, cut the head of the fish.) 3. 머리가 아파요. (I have a headache) 4. 내 머리가 엉켰어요. (My hair got tangled.)