woolly plant louse vs aphid

woolly plant louse and aphid both are nouns.

Word	Noun	Adjective	Verb	Adverb
woolly plant louse	Yes	No	No	No
aphid	Yes	No	No	No

As nouns, aphid is a hypernym of woolly plant louse; that is, aphid is a word with a broader meaning than woolly plant louse:

woolly plant louse: secretes a waxy substance like a mass of fine curly white cotton or woolly threads
aphid: any of various small plant-sucking insects

woolly plant louse (noun)	aphid (noun)
secretes a waxy substance like a mass of fine curly white cotton or woolly threads	any of various small plant-sucking insects