little clubmoss vs club-moss

little clubmoss and club-moss both are nouns.

Word	Noun	Adjective	Verb	Adverb
little clubmoss	Yes	No	No	No
club-moss	Yes	No	No	No

As nouns, club-moss is a hypernym of little clubmoss; that is, club-moss is a word with a broader meaning than little clubmoss:

little clubmoss: of northern Europe and America; resembling a miniature fir
club-moss: primitive evergreen moss-like plant with spores in club-shaped strobiles

Other hypernyms of little clubmoss include club moss, lycopod.

little clubmoss (noun)	club-moss (noun)
of northern Europe and America; resembling a miniature fir	primitive evergreen moss-like plant with spores in club-shaped strobiles