The Surprising Difference Between Sweet Potato and Yam

Which one have you been eating this whole time? There's only one way to find out.

By Emma Kumer, Digital Editorial Intern

Sweet potatoes sitting in a hanging metal dish against a forest backdrop

Shutterstock / M181

Hold onto your hats, because I'm about to drop some knowledge that might blow you away: Sweet potatoes and yams are not the same things. And most likely, you have never tasted a yam.

If you're as stunned by this news as I was, you'll want to know the truth. What have you been serving on your Thanksgiving dinner table? Did you think that sweet potato casserole was really filled with yams? Let's find out.

What's the Difference?

Sweet potatoes are the orange or copper-tan root vegetable you'd find at most grocery stores. They're a member of the morning glory botanical family. Yams, on the other hand, are related to lilies, palms and grasses. They grow primarily in the tropics and can usually be found only in ethnic grocery stores in the U.S. And neither one is really a potato.

Fun fact: These tubers aren't potatoes. The term "sweet potato" is a misnomer. Real potatoes like your trusty russet belong to the nightshade family.

Not sold yet? You can distinguish a yam from a sweet potato before you even bite in. Sweet potatoes have thin, smooth skin and orange or white flesh. Yams have rough, dark skin with an almost hairy texture, and the flesh inside is often white or purple. While you can find potato-sized varieties of both, yams are typically larger and can be up to five feet long!

And those reddish-brownish garnet yams? They're sweet potatoes with a false identity.

The taste is equally distinguishing. Sweet potatoes are flavorful and moist while yams are often starchy and dry. Looks like it's a good thing we don't use them for our sweet potato pie.

So Why Do Some People Refer to Sweet Potatoes as "Yams"?

Let's take a look at history, shall we? Back in pre-Civil War America, grocers typically only sold white-fleshed sweet potatoes. When the orange variety was introduced into the market, sellers wanted to distinguish the new species from the old. Instead of explaining how the two sweet potatoes were actually varieties of the same plant, producers and shippers began calling the orange ones "yams," after the African word nyami meaning "to eat."

Today, you might still find produce labeled as yams in a grocery store, but more likely than not, it's mislabeled.

Now that you know the difference, impress your family across the dinner table by explaining that you could never make your extra-crunchy sweet potato fries with yams! And while you're at it, check out our list of amazing ways to love sweet potatoes. They'll win over even the pickiest of eaters!