Minky is polyester, 58-60" wide, very stretchy along the crosswise axis, super soft and has a slinky feel. It does not shrink when washed. it sheds when you cut it. It comes in mostly solids, some with dimensional dots on it, and some prints. Most colors and prints are baby and kid oriented.

Flannel is cotton 42-44" wide, usually shrinks when washed, is soft but can pill, comes in many, many colors and prints for all ages. It "rags" well if you don't finish the edges, hence is good for quilts or projects where you want a fringed ragged edge. You can use it for a batting for lightweight quilts. Always prewash it before quilting to take the extreme shrink factor out of the equation which could badly distort your finished project after it's washed. There is some flannel that is soft and is polyester, mostly used for children's sleepwear. I wouldn't use it for quilting.