animal group vs herd

animal group and herd both are nouns.

Word	Noun	Adjective	Verb	Adverb
animal group	Yes	No	No	No
herd	Yes	No	Yes	No

As nouns, herd is a hyponym of animal group; that is, herd is a word with a more specific, narrower meaning than animal group:

animal group: a group of animals
herd: a group of cattle or sheep or other domestic mammals all of the same kind that are herded by humans

Other hyponyms of animal group include team, brood, flock, flock, fold, pack, pod, pride, clowder, school, shoal, caste, colony, warren, breed, stock, strain, drove, litter.

animal group (noun)	herd (noun)
a group of animals	a group of cattle or sheep or other domestic mammals all of the same kind that are herded by humans
	a group of wild mammals of one species that remain together: antelope or elephants or seals or whales or zebra
	a crowd especially of ordinary or undistinguished persons or things

animal group (verb)	herd (verb)
	move together, like a herd
	cause to herd, drive, or crowd together
	keep, move, or drive animals