저는 뉴욕에서 자란 46살의 사람입니다. A SHEET means a bed sheet which is the thin sheet which goes on top of you when you are asleep. A FITTED SHEET is the one with elastic that covers the matress and goes under you. A BLANKET is made of wool (양모), is one layer, and covers you in the spring or fall. To me, a COMFORTER and a QUILT are the same thing: A thick blanket for the winter with two layers and filled with a warm material in between. A BED COVER is not for sleeping and is just to make the bed look nice during the day. It is usually removed when you go to sleep.