It is not hard to find differences in their looks. Yams were generally rough and dark brown like tree bark and their flesh is white, purple, or reddish. They are also more cylindrical and long. Sweet potatoes are smoother with skin that is usually orange, red or tan and flesh is bright orange, yellow or purple. They tend to be shorter and tapered on each end. This visual information is useful particularly in the shopping region where labeling can be confusing.
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