fire fighter vs ranger

fire fighter and ranger both are nouns.

Word	Noun	Adjective	Verb	Adverb
fire fighter	Yes	No	No	No
ranger	Yes	No	No	No

As nouns, ranger is a hyponym of fire fighter; that is, ranger is a word with a more specific, narrower meaning than fire fighter:

fire fighter: a member of a fire department who tries to extinguish fires
ranger: an official who is responsible for managing and protecting an area of forest

Other hyponyms of fire fighter include fire chief, fire marshal, fire warden, forest fire fighter.

fire fighter (noun)	ranger (noun)
a member of a fire department who tries to extinguish fires	an official who is responsible for managing and protecting an area of forest
	a member of a military unit trained as shock troops for hit-and-run raids