Yam vs. Sweet Potato: What's the Difference?
| Yam | Sweet Potato | |
|---|---|---|
| Plant family | Dioscoreaceae (a monocot) | Convolvulaceae, the morning glory family (a dicot) |
| Skin | Rough, bark-like, hard to peel raw | Thin, smooth |
| Flesh | Starchy, dry, white to purple | Moist, sweet, orange (most common variety) |
| US grocery labeling | Rare, true yams are uncommon in US stores | What's almost always sold as "yam" in the US |
Verdict
If you bought it at a typical US supermarket labeled "yam," it's almost certainly a sweet potato, true yams are a different plant entirely and are mostly found in African, Caribbean, and Asian specialty markets.
Yam
A true yam is a starchy tuber from a completely different plant family than the sweet potato, with rough, bark-like skin and drier, starchier flesh. They're a staple crop across Africa, the Caribbean, and parts of Asia.
Sweet Potato
What most people in the US actually mean by "yam", a naturally sweet root vegetable with moist, orange flesh (though white and purple varieties exist too), from a completely different plant family than true yams.
FAQ
Why does the US mislabel sweet potatoes as yams?
When orange-fleshed sweet potatoes were introduced to US markets, producers used "yam" to distinguish them from the paler sweet potato varieties already sold, the label stuck even though true yams are a different plant entirely.
Can I substitute one for the other in a recipe?
In practice, most US recipes calling for "yams" mean sweet potatoes and the two are used interchangeably in American cooking, true yams, when available, behave differently (starchier, less sweet) and may need adjusted cook times.