Are red velvet ants wasps or ants?

They are a type of wingless wasp. The females are wingless anyway. They are in the family Mutillidae, in case you want to look them up.

But common names are misleading and often nonsensical. A lot of the questions posted about "red velvet ants" seem to be dealing with real ants, so-called "velvety ants" and that is another matter. But real velvet ants are wasps other than ants (which actually are wasps of sorts as well, but never ind that for now).