Yams vs Sweet Potatoes: What's the Difference?

Are yams and sweet potatoes the same? The names are sometimes used interchangeably, but don’t let that fool you. Both of these colourful tubers are quite different and it pays to know which is which before you start cooking with them.

What are yams (varieties, benefits, nutritional facts)

Yams originated in Africa, Asia and the Caribbean independently, so it may come as no surprise to hear that they can vary greatly in appearance. There are over 600 varieties of yams. Some look more like the branch of a tree than a vegetable, with a thick, fibrous skin resembling bark. Others look more similar to sweet potatoes, which likely explains the confusion. They come in all shapes and sizes too, with some no larger than a small potato, while the heaviest yam on record was a whopping 130 pounds.

Yams are a member of the grass family, which might seem surprising at first, but makes sense when you consider their barky skin in comparison to other grasses like bamboo and sugarcane. Despite their differences, all yams are incredibly starchy and, to those who know how to use them, versatile too.

Yams are a fat-free, high-carb ingredient. They’re also rich in fibre, potassium and manganese, so good for digestion, metabolism, and bone and heart health.

Yams contain a decent amount of vitamin C to boost your immune system, and copper, which is crucial for absorbing iron. That makes yams a great choice to serve with meats and/or greens.

What are sweet potatoes (varieties, benefits, nutritional facts)

Despite their name, sweet potatoes aren’t actually potatoes at all. Their composition of sugars and starches is quite different, which you may have noticed from cooking them. That’s why they generally cook quicker, caramelise better, and go limp if you try making fries with them without adding starch.

Sweet potatoes actually belong to the morning glory family – that’s right, the flowers – and there are various types of different colours across both “firm” and “soft” varieties. Europeans and North Americans are almost certainly most familiar with the orange Beauregard and garnet varieties, but there are also varieties that look more like common potatoes, such as the Hannah, and purple varieties, like the Okinawa, as well as outliers like the Satsuma-Ito, which has purple skin and yellow flesh.

Like yams, sweet potatoes are also a good source of fibre and vitamin C, and contain a decent amount of iron too. But sweet potatoes also contain beta-carotene, which your body converts into vitamin A. That means as well as benefiting immune, digestive and blood functions, sweet potatoes can be good for eye health too. (And if that’s of particular importance to you, it’s worth noting that purple sweet potatoes also contain anthocyanins – a family of antioxidants – which are also good for the eyes.)

Additionally, sweet potatoes also contain selenium, a micronutrient that’s essential for thyroid health, and they also contain more protein than yams. They’re also high in carbohydrates, of which more is sugar (hence the sweet taste).

The differences between them

The confusion between sweet potatoes and yams originates in the United States, which originally only produced 'firm' varieties commercially. Once 'soft' varieties were introduced to American farms, so too was a need to differentiate.

Early on, slaves working American farmlands began referring to the soft sweet potatoes as 'yams', as they more closely resembled the yams in their respective African homelands. The name stuck and, by 1930, Louisiana farmers were selling 'yams' in order to stand out in a market flooded with sweet potatoes. But what they were selling were not yams at all.

So how do you tell the difference? Well, real yams have a tough fibrous brown skin, similar to tree bark. The skin of sweet potatoes looks more like that of regular potatoes, albeit in different colours.

It’s important to choose correctly for the recipe you’re using because yams and sweet potatoes are very different. Sweet potatoes have a moist flesh that softens greatly when cooked. Unsurprisingly, they’re also quite sweet. Yams, on the other hand, have a dry and starchy flesh with a more neutral flavour. They taste nowhere near as sweet and, because they can be quite fibrous, may require extensive preparation depending on what you’re making with them.

These differences mean that sweet potatoes are better suited to providing their own distinct flavour to a dish, whereas yams are often used as a supporting texture to which other flavours are added.

Recipes

Sweet potatoes make for terrific side dishes, such as this simple sweet potato and chicken puree or these mashed sweet potatoes, which are perfect for Thanksgiving dinner. 

On the heartier side, these oven-baked sweet potatoes and beetroots make for a delicious lunch all by themselves, but they also work great served alongside a juicy steak or roast chicken. Alternatively, try this baked sweet potato with beetroot cream recipe instead.

Sweet potatoes also work well in desserts. See for yourself with this sweet potato ice cream recipe or try making these sweet potato cupcakes with a beetroot frosting.

When it comes to yams, you can keep it simple with this roasted yams recipe if you want, but we’d recommend turning to an expert of soul food. Look no further than Rosie Mayes’ I Heart Recipes blog, where you’ll find this mouthwatering recipe for authentic baked candied yams.

It seems clear that there’s a place for both sweet potatoes and actual yams in your kitchen, so have fun cooking with both. And don’t forget to click here to discover 50 more foods for the future.