ranger vs firefighter

ranger and firefighter both are nouns.

Word	Noun	Adjective	Verb	Adverb
ranger	Yes	No	No	No
firefighter	Yes	No	No	No

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

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

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

ranger (noun)	firefighter (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