climber vs mountaineer

climber and mountaineer both are nouns.

Word	Noun	Adjective	Verb	Adverb
climber	Yes	No	No	No
mountaineer	Yes	No	Yes	No

As nouns, mountaineer is a hyponym of climber; that is, mountaineer is a word with a more specific, narrower meaning than climber:

climber: someone who climbs as a sport; especially someone who climbs mountains
mountaineer: someone who climbs mountains

Other hyponyms of climber include escalader, mountain climber, cragsman, rock climber.

climber (noun)	mountaineer (noun)
an iron spike attached to the shoe to prevent slipping on ice when walking or climbing	someone who climbs mountains
someone who climbs as a sport; especially someone who climbs mountains
someone seeking social prominence by obsequious behavior
someone who ascends on foot
a vine or climbing plant that readily grows up a support or over other plants

climber (verb)	mountaineer (verb)
	climb mountains for pleasure as a sport