ranger vs fire fighter

ranger and fire fighter both are nouns.

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

As nouns, fire fighter is a hypernym of ranger; that is, fire fighter is a word with a broader meaning than ranger:

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

Other hypernyms of ranger include fire-eater, firefighter, fireman, functionary, official.

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