As with a lot of words, they change in meaning as time moves along. Fabric/material. I remember when a quilt was covered by a bedspread. Quilts were strictly a utilitarian thing and made use of scraps of fabric (material?). Now it's the bedspread! And remember when chenille bedspreads went out of vogue? Nowadays it's "cool" to actually make it!
Now, what's the difference between a quilt and a comforter? We don't hear the word comforter much any more. My idea is that a comforter has a thicker batt and is tied, not quilted. What do you say?