Comforter sets usually contain 4pcs, 6pcs or 8pcs sheets and pillowcases or pillowshams, packed in one individual bag, which would be customized.
And the quilt cover could be made of different material like 100% cotton from 180 thread count to 1000 thread count, 100% polyester from 65gsm to 95gsm (oe even 120gsm if you need), polycotton, peachy fabric, etc., and the fillings are usually 100% polyester.