mountain man vs pioneer

mountain man and pioneer both are nouns.

Word	Noun	Adjective	Verb	Adverb
mountain man	Yes	No	No	No
pioneer	Yes	No	Yes	No

As nouns, pioneer is a hypernym of mountain man; that is, pioneer is a word with a broader meaning than mountain man:

Other hypernyms of mountain man include adult male, man.

mountain man (noun)	pioneer (noun)
a man who lives on the frontier	one of the first colonists or settlers in a new territory
	someone who helps to open up a new line of research or technology or art

mountain man (verb)	pioneer (verb)
	open up and explore a new area
	open up an area or prepare a way
	take the lead or initiative in; participate in the development of