There are two main types of sweet potatoes. The one most commonly called a sweet potato has flesh that is relatively dry and fluffy, with a yellow color and starchy texture. Sweet potatoes that are moister, sweeter, more slender, and have skins that range from orange to purple are often mistakenly referred to as yams. In fact, they are another variety of sweet potato. True yams, which are grown in the tropics, are almost ivory in color, and are more starchy than sweet.
Sweet potatoes are sold either fresh or canned. The canned ones are either vacuum-packed or packed in a syrup.