cankerworm vs caterpillar

cankerworm and caterpillar both are nouns.

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

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

cankerworm: green caterpillar of a geometrid moth; pest of various fruit and shade trees
caterpillar: a wormlike and often brightly colored and hairy or spiny larva of a butterfly or moth

cankerworm (noun)	caterpillar (noun)
green caterpillar of a geometrid moth; pest of various fruit and shade trees	a wormlike and often brightly colored and hairy or spiny larva of a butterfly or moth