emperor vs saturniid moth

emperor and saturniid moth both are nouns.

Word	Noun	Adjective	Verb	Adverb
emperor	Yes	No	No	No
saturniid moth	Yes	No	No	No

As nouns, saturniid moth is a hypernym of emperor; that is, saturniid moth is a word with a broader meaning than emperor:

emperor: large moth of temperate forests of Eurasia having heavily scaled transparent wings
saturniid moth: large brightly colored and usually tropical moth; larvae spin silken cocoons

Other hypernyms of emperor include saturniid.

emperor (noun)	saturniid moth (noun)
large richly colored butterfly	large brightly colored and usually tropical moth; larvae spin silken cocoons
large moth of temperate forests of Eurasia having heavily scaled transparent wings
red table grape of California
the male ruler of an empire