Yams are considered to belong to the group of potatoes. However, yams have higher moisture content than potatoes. Their skin is like that of tree barks and harder than that of ordinary potatoes.
The inside of yams is white however, this might depend on the type. There is no doubt that the popularity of this sweat African food is spreading to most parts of the world as can be seen by the many people who are taking a liking to this traditionally nutritious food.