"Sweet potatoes are high in vitamins A and C, calcium, iron and fiber, but yams pale in comparison, but they are a good source of potassium, manganese, vitamin C and fiber," Phil Lempert, a food industry analyst, trend watcher and creator of supermarketguru.com, said in a statement.
Yams and sweet potatoes can be stored in a dry cool cupboard -- 55 degrees F -- for up to three to four weeks. Do not refrigerate.
"However, nearly all 'yams' sold in the United States are actually sweet potatoes, even though stores may call them 'garnet' yams," Lempert said.
When shopping for yams and sweet potatoes look for tight, unwrinkled, firm skins and no blemishes and avoid potatoes with bruises that cannot be cut away, as they impact flavor and nutrition, Lempert said. "Prime season is October to January, but sweet potatoes are available fresh and canned -- often labeled erroneously as yams.
"If seeking true yams, check Latin American or Caribbean markets where they are sometimes called boniato and have brown or black skin, similar to tree bark and off white, purple or red flesh depending on the variety," Lempert said. "Yams have higher moisture content and more natural sugar than the sweet potato. Raw yams are toxic."