I was telling my aunt today that I'm making sweet potato pie on Sunday for Jim. She said to use YAMS instead of sweet potatoes. She said they taste the same but yams are much more healthy.
Ok so my question is ... what the heck is a YAM?

And do they taste the same as sweet potatoes? I want this to come out YUMMY tasting, so maybe I should just stick to regular sweet potatoes. Any suggestions?