An archetype refers to a generic version of a personality or person and is neutral.
While a stereotype refers to the attributes that people think characterize a group, and is usually negative. Additionally a stereotype has little to do with the individual, and so mostly tries to characterise them based on group affiliation or association. In other words, inferred characteristics.
With a persona, you're describing relevant attributes of some typical users, not inferring attributes based on some group affiliation or prejudice. Hence, a persona is better described as an archetype.
It's worth noting that we often include aspects that aren't relevant in a persona in an attempt to give the persona an identity. Things like name, favourite colour, gender etc.
By way of examples:
Archetypes:
Novice user
Engineer (i.e. technical)
Prioritises efficiency
Educated
Stereotypes:
Asian
From the developing world
Woman