simple sugars have single unit of carbon chain which can have 3,4,5,6,7 etc. no. of carbons, one or two functional groups, also the hydroxyl groups attached to them.
ex. glucose and fructose, ribose and more
but the starch moiety have multiple monomers of glucose; called as monosaccharides. and they also are bounded in a branched and linear manner with glycosidic linkage.