Cotton Towel is a [woven] fabric with long loops that can absorb large amounts of water. Its content is usually 100% cotton, but may sometimes contain polyester.
French Terry is a fabric, used in men's, women's and children's clothes. One of its sides is flat, while the other side is with cross loops. It is either 100% cotton or contains polyester with elastaine (lycra). It is often warpknitted, and the term French Terry is colloquially used for all warp knitted Terry.