Yams and sweet potatoes are not the same vegetable and actually belong to completely different plant families with distinct characteristics. True yams are starchy tubers native to Africa and Asia with rough, bark like skin and dry flesh, whereas sweet potatoes feature smooth skin and sweet, moist flesh. Most American grocery stores incorrectly label orange fleshed sweet potatoes as yams due to historical marketing practices. True yams are rarely found in standard local supermarkets.