Yams and sweet potatoes are often confused but are actually different plants. The name "yam" was given to sweet potatoes in North America by enslaved Africans who called them by their word for yam, "nyami". True yams are only found in tropical regions and can grow much larger than sweet potatoes. While stores often label sweet potatoes as yams, true African yams would be found in African, Caribbean, or Asian markets. Yams have a brown bark-like peel while sweet potatoes have a smoother skin.