Here in the US, we often use these two terms interchangeably, but there really is a difference. The main difference is in the filling, and a duvet has a removable cover called a duvet cover, and a comforter doesn’t.
What is a comforter?
A comforter is like a thick blanket. A comforter is fluffy like a down-filled blanket, but it has a lighter synthetic fiber filler which is machined stitched to keep the filler evenly distributed. The stiching is why some people also call a comforter a quilt.
When we say quilt, we usually mean a unique one of a kind, handmade blanket which was traditionally hand quilted, but in modern times can also be machine quilted.
Unlike a duvet, the comforter only forms one piece of all of your bed linens. It is intended to be used with sheets, which are easier to wash than the bulky blanket, and since there is a layer between you and your comforter, it has to be washed less often.
Comforters are usually sold in bedding sets that have coordinating separates such as pillow shams and maybe a dust ruffle, which makes it easy to get a complete look.
Comforters are designed to be larger than beds, so they will hang over the sides. Duvets, on the other hand, fit the bed more snugly.
See a selection of comforters here.
What is a duvet?
A duvet is a soft flat bag filled with down, feathers, wool, or a synthetic alternative. It is protected with a removable cover, called the duvet cover. The duvet should fit snugly inside the duvet cover.
The term duvet originated in France. Duvets were originally made from the down feathers of birds because of their usefulness as a thermal insulator, keeping you warm and cozy in cold climates.
Many people do not use sheets and other blankets with a duvet, since it is so warm. It’s intended to be used as a single covering instead of a combination of sheets, blankets, and bedspread.
What is a duvet cover?
Like a pillowcase covers a pillow, a duvet cover is a protective layer that slips over the duvet and usually has a zipper closure. Because duvets and comforters can be too large for some home washers, they are expensive and difficult to clean. Duvet covers protect your duvet during use and are easily removed and can be washed in most home washing machines.
Both comforters and duvet covers are so pretty, most people don't cover them with a beadspread.
See a selection of duvet covers here.