Although the soft, orange sweet potato is often called a ''yam'' in parts of North America, the sweet potato is botanically very distinct from a genuine yam (Dioscorea), which is native to Africa and Asia and belongs to the monocot family Dioscoreaceae. To add to the confusion, a different crop plant, the oca (Oxalis tuberosa, a species of wood sorrel), is called a ''yam'' in many parts of Polynesia, including New Zealand.

What's the best answer to this question: are sweet potatos and yams the same thing?
no