One tablespoon of standard sucrose, or table sugar, contains approximately 48 calories and about 12 grams of sugar.
Starch is a polymer of the monosaccharide glucose: Starch is the principal polysaccharide used by plants to store glucose for later use as energy. Plants often store starch in seeds or other specialized organs; for example, common sources of starch include rice, beans, wheat, corn, potatoes, and so on.
Starch, therefore, is a polysaccharide. Specifically, starch is composed of the sugar glucose. Plants use glucose to produce energy, but they're not always making glucose, just as we're constantly eating to get our energy. Much like we store up energy reserves after eating, so do plants.