A blanket is a large piece of cloth covering a bed, which helps keep you warm when you sleep.
A comforter is a very thick blanket, usually filled with soft and fluffy material inside. It will keep you extra-warm... and comfortable!
A quilt is a type of blanket made by sewing different pieces of fabric together, often with a colorful and decorative design. Quilts can be used as blankets for sleeping, or they can be hung on the wall as a type of art.