Flannel

Flannel is a soft woven fabric, of various fineness. It usually does not have a nap, and instead gains its softness through the loosely spun yarn it is woven from. It is commonly used to make clothing, bed sheets, and sleepwear.
Flannel was originally made from carded wool or worsted yarn, but is now often made from either wool and cotton, or wool and synthetic fibre.
Flannelette.
Flannelette is a light, napped cotton fabric imitating the texture of flannel. The weft is generally coarser than the warp. The flannel-like appearance is created by creating a nap from the weft; scratching it and raising it up. Flannelette can either have long or short nap, and can be napped on only one or two sides. It comes in many colours, both solid and patterned.
Weave.
Flannel, flannelette and cotton flannel can be woven in either a twill weave or plain weave. The weave is often hidden by napping on one or both sides. After weaving, it is napped once, then bleached, dyed, or otherwise treated, and then napped a second time.