animal group vs strain

animal group and strain both are nouns.

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

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

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

animal group (noun)	strain (noun)
a group of animals	an effortful attempt to attain a goal
	the act of singing
	an intense or violent exertion
	the general meaning or substance of an utterance
	a succession of notes forming a distinctive sequence
	a special variety of domesticated animals within a species
	(biology) a group of organisms within a species that differ in trivial ways from similar groups
	(physics) deformation of a physical body under the action of applied forces
	injury to a muscle (often caused by overuse); results in swelling and pain
	(psychology) nervousness resulting from mental stress
	difficulty that causes worry or emotional tension

animal group (verb)	strain (verb)
	cause to be tense and uneasy or nervous or anxious
	alter the shape of (something) by stress
	to exert much effort or energy
	use to the utmost; exert vigorously or to full capacity
	remove by passing through a filter
	separate by passing through a sieve or other straining device to separate out coarser elements
	become stretched or tense or taut
	rub through a strainer or process in an electric blender
	test the limits of