I've never seen a yam. They are rare in the USA. I know some people call sweet potatoes yams but they are a completely different thing.
Are they orange inside and long? The sweet potatoes in some stores aren't orange inside but kind of a cream color. It gets confusing, because different stores sell different looking sweet potatoes.
Most sweet potatoes are orange inside but there is a variety that is white inside. You can google sweet potato and yam images and see what they look like.
@Sheldon Scott , what is this? This was a half of a yam or sweet potato that I have in my house. I forget what I bought it as...think sweet potato.
our sweet potatoes are orange...I use them a lot and have them as sweet potato mash or fries...they are so much more nutritious than ordinary potatoes and you don't have to add butter to them when you mash them either.. I keep frozen fries and mashed sweet potatoes in the freezer at all times but apparently according to this link sweet potatoes can be either orange or creamy flesh, and mainly called Yams in the USA.. http://www.bbcgoodfood.com/glossary/sweet-potato
They are mostly called sweet potatoes in the USA but there are still some who haven't learned the difference. I'm trying to teach Chrissy.