Yams Vs. Sweet Potatoes: What’s The Difference? If you’re not arguing about politics or whether or not it’s time for Grandma to get some more grandchildren, there’s one topic that’s always guaranteed to make a splash at the Thanksgiving dinner table: Are those yams or sweet potatoes in your holiday casserole? Wait a second, aren’t they the same thing? Not according to the dictionary! WATCH: Why Are There So Many Definitions For The Word "Sweet"? Previous Next Yams vs. sweet potatoes Yams and sweet potatoes are in fact two different root vegetables. And, unless you shop in a specialty store, it’s likely that you’ve only purchased sweet potatoes (even if they were labeled as yams). Yams are the tuberous roots of the genus Dioscorea. They’re native to parts of Asia and Africa and can grow to weigh over 100 pounds. The word yam is derived, via Portuguese or Spanish, from a West African language called Wolof. The Wolof word nyam means “to sample” or “taste.” Similar words in other African languages for yam mean “to eat” and “to chew.” Like the yam, the sweet potato is grown for its edible root. But, unlike the yam, it is not part of the Dioscoreaceae family. Sweet potatoes are native to South America, and they were the main source of nourishment for early Europeans in the Americas. So, why do we get them confused? Confusing consumables In general, there are two kinds of sweet potatoes. The firm, white variety was cultivated first in the United States. But, once a soft variety was developed for a commercial market, people wanted a way to distinguish between the two. Because of their resemblance to yams grown in Africa, African slaves in North America had already been referring to sweet potatoes as yams. So, the name stuck. The US Department of Agriculture tries to help confused consumers by requiring that sweet potatoes that are called yams are also labeled sweet potatoes. We’re not sure that makes it any less clear … But, whether you call them yams, sweet potatoes, or yams-that-are-actually-sweet-potatoes is up to you!