"Ideal" vs "archetype" vs "role model" vs "prototype"

The term archetype may refer to an ideal, but not necessarily so. The American Heritage Dictionary gives this definition and example as its first:

An original model or type after which other similar things are patterned; a prototype: “ ‘Frankenstein’ . . . ‘Dracula’ . . . ‘Dr. Jekyll and Mr. Hyde’ . . . the archetypes that have influenced all subsequent horror stories” (New York Times).

An archetype can be a model of excellence, but also a model of evil. Ideal almost always suggests something positive.

Merriam–Webster’s first definition is:

the original pattern or model of which all things of the same type are representations or copies : prototype; also: a perfect example

In this case, perfect indicates most exact, not necessarily good.

Prototype is actually closer to archetype. While they are often interchangeable, prototype is more often used for inanimate objects. Archetype is usually used when referring to living things or characteristics of living things, although the earliest uses may have been for objects. See for example the Online Etymology Dictionary.

Note that this source (and others) also describes a specific use of archetype in Jungian psychology, referring to an inherited idea or mode of thought derived from the experience of the race and present in the unconscious of the individual.

An archetype is a universally understood symbol. The symbol of 'hero' for example, appears in every culture. So do personifications of good and evil.

An ideal is a perfect form of something. The ideal table is a perfect table.

There is no reason why an ideal cannot be an archetype, though I can't think of one off hand, and to some extent the ideas overlap. An archetype is an idea, like an ideal. It could also, in some way, be a prototype, insofar as all heroes are versions of an archetypal hero.

The differences are that an archetype is not necessarily perfect like an ideal, just recognisable, and not so much copied by all cultures as created by all cultures - the archetypal hero is the result of all culture having heroes, not the cause of them.