Sweet potato or yam?

Dear Heloise:

What is the difference between a yam and a sweet potato?

Nora P., Stone Mountain, Ga.

Sweet potatoes usually are sweeter than yams. Yams are starchier.

Sweet potatoes contain calcium, iron, protein, beta carotene, sodium, vitamin A and more sugar and water than yams. Yams have more fiber, potassium and vitamins C, B6 and E but more fats and carbs.

Sweet potatoes are readily available in most grocery stores, but yams usually are more available in international markets.

There are two main varieties of sweet potatoes in the U.S. One is pink-skinned and orange inside; the other is golden-skinned and white inside. Yams' outer skins usually are dark brown or light pink. The insides can be pink, white, yellow or purple.