Do you know the difference between a yam and a sweet potato? Most grocery stores offer two similar-looking tubers — some labeled as yams, and some as sweet potatoes.

Would you be surprised if I told you that all those times you thought you were eating yams, you were likely eating a sweet potato, and that you probably haven’t ever actually had a true yam? And yet yam and sweet potato do mean different things in grocery stores. Here’s the scoop on these tubers, with tips for getting the one you want at the grocery store.

While much of the confusion stems from these names being used interchangeably in U.S. markets and in recipes, sweet potatoes and yams are actually two distinct and very different vegetables.

A Yam Is Probably Not a Yam

Let’s clear up one very important point: sweet potatoes are not a type of yam, and yams are not a type of sweet potato. They are both tuberous root vegetables that come from a flowering plant, but they are not related and actually don’t even have a lot in common.

What’s a (Real) Yam? 

Yams are native to Africa and Asia, with the majority of the crop coming from Africa. They are related to lilies, and can be as small as a regular potato or ridiculously jumbo in size (some grow five feet long!). Yams have a cylindrical shape with blackish or brown, bark-like skin and white, purple or reddish flesh.

Compared to sweet potatoes, yams are starchier and drier. True yams can be tough to find. They aren’t carried in many local grocery stores, so your best chances of finding them are in international and specialty markets.

What’s a Sweet Potato?

There are many varieties of sweet potatoes, which come from the morning glory family. Skin color can range from white and yellow to red, purple and brown, while the flesh can be white, yellow, orange or even orange-red. These vegetables have an elongated shape with tapered ends.

Among the numerous varieties of sweet potatoes grown in the U.S. there are two major types:

1. Firm sweet potatoes, which have golden skin and paler flesh. 
2. Soft sweet potatoes, which have copper skin and orange flesh. 

The two types of sweet potatoes cook differently. After cooking firm sweet potatoes still remain firm and a little waxy, while the soft variety becomes creamy, fluffy, and moist.

What Is the Grocery Store Calling a Yam? 

So, if true yams aren’t very common in the United States, here’s the big question: what is the grocery store calling a yam? And is there any real difference between what a grocery store calls a yam and a sweet potato?

Even though these “yams” aren’t true yams, there is a difference between the two, and you can actually shop smarter by knowing the difference in these labels.

Here’s an interesting little history lesson to explain why there’s so much confusion. As we mentioned above, there are two types of sweet potatoes — “firm” and “soft.” The firm variety was the first to be produced in the U.S., so when “soft” sweet potatoes began to be produced commercially, there was a need to differentiate it from its firm counterpart.

Since the “soft” sweet potatoes slightly resembled true yams, they picked up the name and became what you see labeled as “yams” in most U.S. grocery stores.

Ironically, when you want a classic baked sweet potato, with a crisp skin and fluffy orange flesh, or sweet potatoes for Thanksgiving sweet potato casserole, what you should buy will be probably labeled yam. Even though it’s not a yam. It’s a sweet potato. The soft kind.

But just to throw one more wrinkle into this: Grocery stores often go rogue with labeling. We’ve bought “yams” (which are really sweet potatoes) that were indeed labeled as sweet potatoes.

The takeaway: Know what kind of sweet potato you want for your recipe, and be alert to the yam/sweet potato labeling concept, but also use your eyes to look at the color of the skin and the flesh, if possible.