plant louse vs homopteran

plant louse and homopteran both are nouns.

Word	Noun	Adjective	Verb	Adverb
plant louse	Yes	No	No	No
homopteran	Yes	No	No	No

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

plant louse: any of several small insects especially aphids that feed by sucking the juices from plants
homopteran: insects having membranous forewings and hind wings

Other hypernyms of plant louse include homopterous insect.

plant louse (noun)	homopteran (noun)
any of several small insects especially aphids that feed by sucking the juices from plants	insects having membranous forewings and hind wings