louse vs common louse

louse and common louse both are nouns.

Word	Noun	Adjective	Verb	Adverb
louse	Yes	No	No	No
common louse	Yes	No	No	No

As nouns, common louse is a hyponym of louse; that is, common louse is a word with a more specific, narrower meaning than louse:

louse: wingless usually flattened bloodsucking insect parasitic on warm-blooded animals
common louse: head or body louse

louse (noun)	common louse (noun)
wingless usually flattened bloodsucking insect parasitic on warm-blooded animals	head or body louse
any of several small insects especially aphids that feed by sucking the juices from plants
wingless insect with mouth parts adapted for biting; mostly parasitic on birds
a person who has a nasty or unethical character undeserving of respect