In essence, while a bed sheet is a specific item, bed linen refers to the entire set of bedding fabric products.

A duvet cover encases and protects a duvet. Like an envelope, it has an opening where the comforter or duvet is inserted. Once placed inside, the opening is closed with buttons or occasionally a zipper. Duvet covers are generally very decorative and are available in a wide selection of colors and styles. The duvet cover takes the place of a top sheet in Europe, and some people in the U.S. also use it this way.