work animal vs animal

work animal and animal both are nouns.

Word	Noun	Adjective	Verb	Adverb
work animal	Yes	No	No	No
animal	Yes	Yes	No	No

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

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

work animal (noun)	animal (noun)
an animal trained for and used for heavy labor	a living organism characterized by voluntary movement

work animal (adjective)	animal (adjective)
	marked by the appetites and passions of the body