For starters, everything.
Is it a yam? Or is it a sweet potato? To get to the root of one of the produce aisle's biggest mysteries, let's dig right in: They're not the same thing. Only one of them is orange. They don't taste the same. And chances are you've never even had a yam before. So why all of the confusion?
Consider this a tell-all on tubers.
Where Do They Come From?
While it's true that both yams and sweet potatoes are vegetables and sprout from flowering plants (sweet potatoes from a species of morning glory, and yams from a type of lily), the similarities sputter out there.
"Yams are traditionally grown in Africa, the Caribbean, and Southeast Asia," says Tricia Williams, a chef and founder of Food Matters NYC, a holistic meal delivery service company. "It's unlikely that your local grocery store even carries them. They're often found in ethnic markets." Sweet potatoes, on the other hand, are produced in the United States, primarily North Carolina.
What Do They Look Like?
Grocery stores will often have a few, similar-looking tubers—some labeled as sweet potatoes and some as yams. But to prevent yourself from falling for a yam scam, here's how to know what you're looking at.
In the same way that tomatoes, cauliflower, and other produce can come in different shades and varieties, so can sweet potatoes. There are actually two main types—one with a white flesh (more likely to be found at a farmers' market), and one with a burnt-orange hue inside (the common kind you're used to seeing). This is likely where the mix-up originated. "The confusion between sweet potatoes and yams really comes from the USDA," says Brigitte Zeitlin, R.D., a registered dietitian and founder of BZ Nutrition. "Because there are two types of sweet potatoes, the USDA has labeled the orange-fleshed sweet potatoes as 'yams' to distinguish the two varieties."
Another hint to help you figure out what you've got: A sweet potato's ends are usually tapered. Yams are more cylindrical in shape. The skin of a yam is dark, resembles tree bark, and has a hairy feel to it, and the flesh inside ranges from creamy white to a washed-out purple. It can be the size of a typical potato or grow to as big as 5 feet long (yeah, seriously).
What Do They Taste Like?
It's not likely that you'd ever top a true yam with brown sugar and marshmallows any more than you'd do that with a russet potato. Yams are starchy, and sturdy, so they're great for making fries, Williams says, or they can be used as a white potato replacement in certain soups and dishes. Sweet potatoes, on the other hand, are ideal to serve baked or mashed (or yes, covered with marshmallows), Williams says, although the paler-fleshed variety doesn't cook up as fluffy, and generally tends to be firmer. And the sweet potato lives up to its name—it is indeed sweeter than a yam. Even before you add marshmallows. (Or use them for this Easy Sweet Potato Hash You Can Make In the Microwave.)
Are They Good for You?
From a health perspective: "Both are nutritionally dense," Zeitlin says. "But serving for serving, sweet potatoes come out slightly higher—they pack more protein and fiber." Both of the root veggies are also packed with potassium and vitamins. "The big difference is the amount of vitamin A you get from a sweet potato—one serving gives you 270 percent of your daily vitamin A needs." (A yam offers about 1 percent, Zeitlin says.) Pretty sweet deal since the vitamin plays a big role in eye health, muscle and tissue repair, and keeping your skin bright, Zeitlin adds.
They're two different veggies, people! They taste and look different, not to mention sweet potatoes pack more of a nutritional punch compared to yams. Luckily, that's what you've likely been buying at the grocery store your whole life anyway, no matter what color the flesh is. So eat up! (Like with these morning-changing sweet potato toast recipes.) This time you'll actually know what you're having.