Analogy: duvet is to duvet cover as pillow is to pillowcase. A duvet cover is a protective layer that slips over the duvet and has a closure. Because duvets and comforters can be expensive and difficult to clean, duvet covers are useful because they protect your comforter during use and are easily removed and easy to wash. With duvet covers, you can also quickly and easily change the look of your bed and room without having to completely redecorate. Bedding that, depending on its filling, may be placed on top of a comforter or replace the comforter altogether.
Both comforters and duvets are used to keep warm. What they are called and how they are placed on a bed, exactly, varies by region. The word “duvet” was originally and specifically associated with down feathers. (In French, “duvet” literally means “down,” as in bird plumage.) In contrast, comforters were typically filled with other natural fibers, like cotton, or synthetic fibers, like polyester.
