inchworm vs caterpillar

inchworm and caterpillar both are nouns.

Word	Noun	Adjective	Verb	Adverb
inchworm	Yes	No	No	No
caterpillar	Yes	No	No	No

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

inchworm: small hairless caterpillar having legs on only its front and rear segments; mostly larvae of moths of the family Geometridae
caterpillar: a wormlike and often brightly colored and hairy or spiny larva of a butterfly or moth

inchworm (noun)	caterpillar (noun)
small hairless caterpillar having legs on only its front and rear segments; mostly larvae of moths of the family Geometridae	a wormlike and often brightly colored and hairy or spiny larva of a butterfly or moth