Pop singers sing what’s popular. Artists redefine what’s popular.
Pop singers imitate. Artists originate.
Pop singers need to be consistently good. Artists must be, at least occasionally, surprisingly brilliant. Performance may vary.
People enjoy pop singers who meet expectations. People love artists who blow expectations apart.
It’s enough for a pop singer to do something you enjoyed another pop singer doing. An artist has to do something you believe only they could do. That is what defines them.