pioneer vs mountain man

pioneer and mountain man both are nouns.

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

As nouns, mountain man is a hyponym of pioneer; that is, mountain man is a word with a more specific, narrower meaning than pioneer:

Other hyponyms of pioneer include bushman, backwoodsman, frontiersman, frontierswoman.

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

pioneer (verb)	mountain man (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