beet armyworm vs caterpillar

beet armyworm and caterpillar both are nouns.

Word	Noun	Adjective	Verb	Adverb
beet armyworm	Yes	No	No	No
caterpillar	Yes	No	No	No

As nouns, caterpillar is a hypernym of beet armyworm; that is, caterpillar is a word with a broader meaning than beet armyworm:

beet armyworm: moth larva that eats foliage of beets and other vegetables
caterpillar: a wormlike and often brightly colored and hairy or spiny larva of a butterfly or moth

beet armyworm (noun)	caterpillar (noun)
moth larva that eats foliage of beets and other vegetables	a wormlike and often brightly colored and hairy or spiny larva of a butterfly or moth