The "correct" term is fabric, not cloth, even though the two are used interchangeably. Cloth is the finished form of the fabric. So, when it is measured and cut, it's called fabric, and the material of the finished piece (such as a sail or quilt) may be called cloth. You buy bolts and folds of fabric, not cloth.
I wouldn't know this except for the more than 3,000 bolts of fabric sitting in my store. The little old ladies made fun of me whenever I called it "cloth," and told me that, "you sell fabric, and are not a man of the cloth."