The latter is usually made from a mix of different fabrics, including polyester, rayon, nylon, and acrylics. It’s water-resistant and easy to clean, which explains its popularity as a common upholstery material.
However, microfiber sheets are anything but breathable and can cause you to overheat. In fact, the fabric retains heat so well that you can actually scorch it if you dry it on the hottest heat setting! Especially if you need moisture-wicking properties, then cotton will keep you more comfortable.
On the other hand, microfleece is often made of 100% polyester. It has a slightly softer and fuzzier texture than microfiber, and more closely resembles flannel. It also has a higher pile but is more breathable and lightweight.