range animal vs fauna

range animal and fauna both are nouns.

Word	Noun	Adjective	Verb	Adverb
range animal	Yes	No	No	No
fauna	Yes	No	No	No

As nouns, fauna is a hypernym of range animal; that is, fauna is a word with a broader meaning than range animal:

range animal: any animal that lives and grazes in the grassy open land of western North America (especially horses, cattle, sheep)
fauna: a living organism characterized by voluntary movement

Other hypernyms of range animal include animal, animate being, beast, brute, creature.

range animal (noun)	fauna (noun)
any animal that lives and grazes in the grassy open land of western North America (especially horses, cattle, sheep)	a living organism characterized by voluntary movement
	all the animal life in a particular region or period