ranger vs fireman

ranger and fireman both are nouns.

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

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

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

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

ranger (noun)	fireman (noun)
an official who is responsible for managing and protecting an area of forest	play in which children pretend to put out a fire
a member of a military unit trained as shock troops for hit-and-run raids	a member of a fire department who tries to extinguish fires
	a laborer who tends fires (as on a coal-fired train or steamship)
	a pitcher who does not start the game