Yam vs. Sweet Potato

Yam and sweet potato are root vegetables. Yam is native to Africa and Asia, while sweet potato originates from tropical parts of Central and South America. There are more than 600 varieties of yam and around 7000 varieties of sweet potato that are cultivated worldwide as a source of food. Terms "yam" and "sweet potato" are often used interchangeably, however, these two plants are not closely related and they have only few things in common. Here are basic differences between yam and sweet potato:

Classification

Yam is monocot plant that belongs to the yam family. Sweet potato is dicot plant that belongs to the morning glory family.

Color of the Skin and Flesh

Sweet potato has smooth skin that can be white, yellow, red, purple or brown colored and white, yellow, orange or purple flesh. All types of sweet potato can be divided in two groups: firm and soft. Firm variety is lighter in color and has light yellow flesh. It contains less sugar than soft variety and retains firm, crumbly texture after cooking. Soft sweet potato has dark red (or orange) skin and orange flesh which becomes creamy and moist after cooking. Soft type of sweet potato slightly resembles yam, which is why it is erroneously called (and sold) as "yam" in the USA. Unlike sweet potato, yam has blackish or brown, rough and scaly skin and white, purple or reddish flesh.

Shape and Size of Tuber

Sweet potato has elongated tuber with tapered ends. It is much smaller than yam. Yam is cylindrically shaped. It can be small like regular potato or it can reach weight of 130 pounds and length of 5 feet.

Nutritional Profile

Both yam and sweet potato are good source of vitamins B6 and C. Yam is also good source of potassium, while sweet potato is excellent source of beta carotene and manganese. 100 g of yam contains 118 calories, while 100 g of sweet potato contains 90 calories. Yam is more starchy and dry than sweet potato.

Preparation

Both yam and sweet potato need to be thermally processed before consumption. Yam is often consumed in the form of paste. Powder made of dried yam is used for the preparation of porridge. Some sorts of yam can be fried and consumed as chips. Purple yam is ingredient of various cakes, ice-creams and candies in Asia. Sweet potato is usually consumed in the form of mash potato. It can be also baked, fried, roasted or used for the preparation of soups and pies. Young leaves and shoots of sweet potato are also edible.

Source of Dye

Red type of sweet potato is used as a source of pink, purple and black dye. Obtained dyes have application in textile industry.