Interfaces allow member definitions?

[Frustrated]

Simple question.

What are the difference between an interface and a class?

I'm not talking about what the compiler does with them. I'm
talking about what they were created to do, how they came about
etc.

If you have to explain to someone what a class is and what an
interface is, then you diff that, what is your answer?

vtables should not show up in your explanation(they would if I
didn't mention it and it shows that you are stuck on the
implementation aspect and can't see the forest).