You wait all year to dig into your mom’s Thanksgiving yams with mini marshmallows. While they may be delicious, it turns out they aren’t yams at all. Even though the words “sweet potato” and “yam” have been used interchangeably for decades, there are actually some big differences between the two. Yams vs. sweet potatoes: Are they the same? The answer is a resounding no.

RELATED: The 23 Best Sweet Potato Recipes You Need in Your Life

What Are Yams?

Real yams, native to West Africa and Asia, have tough tree bark-like skin, similar to cassava. Their flesh can vary in color from white to red to purple. They’re popular in West African and Caribbean cuisines, often being served with meat entrees or starring in recipes like yam porridge or dun dun (fried yam). They’re dry and starchy rather than sweet but can be prepared in essentially all the same ways as sweet potatoes, from roasting to frying. (We’d probably table the mini marshmallows though.)

What Are Sweet Potatoes?

When you see sweet potato on a menu in the U.S., what likely comes to mind is orange-fleshed sweet potatoes, which are starchy and have a thin outer skin just like red potatoes and russets but taste sweeter. (Though there are actually many types of sweet potatoes.) They’re native to Central and South America but are now primarily grown in North Carolina.

What’s the Difference?

Yams and sweet potatoes have differences in both appearance, taste and origin. Yet, Americans have come to use the terms interchangeably, almost always in reference to orange sweet potatoes. How did this happen? When Africans were enslaved and brought to the Americas, real yams came with them. Once the yams ran out, white sweet potatoes were the substitute. Enslaved people started calling them “nyami,” a Fulani word meaning “to eat,” which was later anglicized to the word “yam.” Then, in the 1930s, Louisiana started calling its orange sweet potatoes yams to help distinguish and better market its crop from those of other states. And the rest is history.

So, in most American grocery stores today, you’re bound to see lots of sweet potatoes—but they might be labeled yams on the shelf. Real yams may be tough to find; you may have better luck at a specialty grocery store. You can also order them online.

The Health Benefits of Eating Yams and Sweet Potatoes

Yams

Yams are high in fiber (about 5 grams per one-cup serving), fat-free, low in calories and even contain a bit of protein, too. They're packed with vitamins and minerals, like vitamin C, manganese, copper and potassium—one serving contains about 20 percent of your daily recommended amount of each. Potassium and manganese support bone health, while vitamin C boosts your immune system. Copper aids in iron absorption and promotes the production of red blood cells. Since yams are full of antioxidants, they may also reduce inflammation. Yams also contain a compound calls diosgenin, which studies have found to be linked to brain function, neuron growth and improved memory.

Sweet Potatoes

Sweet potatoes have slightly more fiber and protein than yams, as well as more calories, fat and carbs. Each one-cup serving boasts half your daily recommended manganese, more than a quarter of your daily recommended vitamin B6 and potassium, 65 percent of your daily vitamin C and a whopping 769 percent of your daily vitamin A. Vitamin A is crucial for a healthy immune system and gut. Sweet potatoes are great for maintaining healthy vision, as one cup contains seven times the beta-carotene (aka what's used to form light receptors in your eyes) that you need in a day. They're also packed with antioxidants that may have cancer-fighting properties. Purple sweet potatoes in particular have also been linked to improved brain function.

Ready to cook?

Types of Sweet Potatoes to Look for at the Supermarket

Orange Sweet Potatoes

The key ingredient of your favorite fries, autumn pie and go-to work lunch. They’re sweet, soft, moist and versatile across all varieties, though some types will differ slightly in color and flavor. Nevertheless, most orange sweet potatoes are interchangeable in cooking and baking. Their unique flavor and hearty, starchy nature hold up under intense spices and bold ingredients like brown sugar and smoked paprika.

Use them: Overstuffed Sweet Potatoes with Chipotle-Lime Yogurt

White Sweet Potatoes

They may look like regular spuds on the inside, but their outer flesh and oblong shape are a giveaway. Not only are there white sweet potatoes with reddish and purple skin, you might also see some like the O’Henry variety, which are white on the outside too. Their starchiness makes them a bit dry, so cooking them in a creamy or citrusy sauce should help moisten them up.

Use them: Arugula, Fig and Fried White Sweet Potato Salad

Purple Sweet Potatoes

Aren’t they beautiful? Most purple sweet potatoes in the U.S. are Stokes from North Carolina, but Okinawan potatoes from Hawaii are also common. Purple sweet potatoes tend to be denser than other types, but turn rich, starchy and nutty when cooked (some even say wine-like). Roast, fry or sauté them to make sure they keep their purple color.

Use them: Purple Sweet Potato Coconut Curry with Beech Mushrooms and Bok Choy

Types of Yams

There are more than 600 types of yams still being grown today and Africa is home to 95 percent of them. Here are a few types of yams to investigate. They may require more legwork to find but they’re well worth it—Western sweet potatoes don’t come close.

• African yams: You may also see them called puna yams, Guinea yams, tubers or Nigerian yams.

• Purple yams: These are native to Asia and common in countries like Japan, Vietnam and the Philippines. You may recognize them as ube, which has become really popular stateside in ice cream and halo-halo, a Filipino dessert made with crushed ice and evaporated milk.

• Indian yams: Also called suran, this type is most common in tropical and subtropical countries. In India, it’s used in stir-fries, curries and poriyal, a sautéed vegetable dish.

• Chinese yams: Also known as cinnamon vine, Chinese potato and nagaimo, this plant is a climbing vine that’s been used in Chinese herbal medicine for centuries. Try it in stew, fried rice or congee.

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