How to Tell the Difference Between Yams and Sweet Potatoes. Most people seem to be under the impression that yams and sweet potatoes are the same vegetable; they are just known by two different names in different parts of the world. That is not the case.
Look at the shape and size when you want to tell the difference in yams and sweet potatoes. This is the most immediate noticeable difference. A sweet potato has a thin skin and a smooth appearance. Sweet potatoes are short, stubby and have just slightly tapered ends. A yam, on the other hand, is long and cylindrical. Yams can grow to be over 7 feet long. Yams have a rough and scaly skin which somewhat resembles the bark of a tree.
Check the color to tell the difference in yams and sweet potatoes. Yams have a brownish, almost black color to the skin. The flesh (edible part) of a yam is purple or sometimes red. There's an off-white color variety, too. Sweet potatoes have a light yellow skin. The flesh of a sweet potato is pale yellow. Another variety of sweet potato has a thicker, dark orange or almost red skin. The flesh of this variety is bright orange.
Feel the texture for another way to tell the difference in these two tasty vegetables. In your mouth, a bright orange version of the sweet potato has a moist texture. The pale yellow flesh version has sort of a crumbly texture, much like a regular white baking potato. The feel of a yam in your mouth will have a much drier texture.
Taste to tell the difference in yams and sweet potatoes. The dark skin, bright orange version of the sweet potato has a very sweet taste. The lighter skinned, light yellow version of the sweet potato is not quite as sweet. Yams usually have a more starchy taste.