giant silkworm vs caterpillar

giant silkworm and caterpillar both are nouns.

Word	Noun	Adjective	Verb	Adverb
giant silkworm	Yes	No	No	No
caterpillar	Yes	No	No	No

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

giant silkworm: larva of a saturniid moth; spins a large amount of strong silk in constructing its cocoon
caterpillar: a wormlike and often brightly colored and hairy or spiny larva of a butterfly or moth

giant silkworm (noun)	caterpillar (noun)
larva of a saturniid moth; spins a large amount of strong silk in constructing its cocoon	a wormlike and often brightly colored and hairy or spiny larva of a butterfly or moth