fictional animal vs brute

fictional animal and brute both are nouns.

Word	Noun	Adjective	Verb	Adverb
fictional animal	Yes	No	No	No
brute	Yes	Yes	No	No

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

fictional animal: animals that exist only in fiction (usually in children's stories)
brute: a living organism characterized by voluntary movement

Other hypernyms of fictional animal include animal, animate being, beast, creature, fauna.

fictional animal (noun)	brute (noun)
animals that exist only in fiction (usually in children's stories)	a living organism characterized by voluntary movement
	a cruelly rapacious person

fictional animal (adjective)	brute (adjective)
	resembling a beast; showing lack of human sensibility