Cotton and fleece are two of the more common materials in bathrobe construction. While both can be warm and comfortable, they originate from different materials: cotton from natural cotton plants and fleece from polyester, which is a synthetic fabric. One of the biggest differences between the two materials is how effectively they absorb water. Cotton is extremely absorbent, while fleece tends to be much less so. If you use a bathrobe primarily after getting out of the shower or bath, a cotton robe may be a better choice for you than a fleece one.