How does an archetype differ from a stereotype?
An archetype is is an ideal example of something, of which others are less pure or ideal copies. So an archetypal salesman is not just a typical salesman, but one who demonstrates what makes a salesman a salesman, perhaps in extreme ways or extraordinary ways.
A stereotype is more of an ordinary example of something, that seems to fit the expectations of that thing. So a stereotypical salesman would look and behave in all the ways you might expect of a salesman, yet not shine out as expressing salesmanship in any extraordinary way.