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.
Step 1
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.
Step 2
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.
Step 3
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.
Step 4
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.