Although commonly used interchangeably in the United States, the two are actually very different vegetables. Take a look below to learn the difference!  Yams: These vegetables have a cylindrical shape with rough black or brown skin and have white or purple-colored flesh. They’re starchier and drier than sweet potatoes. Sweet Potatoes: Existing in many varieties, sweet potatoes can have skin that is white, yellow, red, purple, or brown, and the flesh varies in shade from white to yellow, or orange. The two main varieties found in the U.S. are firm sweet potatoes and soft sweet potatoes.