Flannel - The softest of the fabrics and also a tiny bit thicker due to the loft of the flannel fibers. This fabric has the very slightest bit of stretch while the others do not.

Canvas - Has a more sturdy feel to it than the other fabrics with comprable thickness to the denim and twill. The "roughest" of the fabrics, but still soft & smooth enough for sensitive newborn skin.

Twill - The smoothest of the fabrics and thin enough to be comfortable on the warmest day.

Denim - Not a true denim, but more like a twill with the look of blue jeans.