club-moss vs fern ally

club-moss and fern ally both are nouns.

Word	Noun	Adjective	Verb	Adverb
club-moss	Yes	No	No	No
fern ally	Yes	No	No	No

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

club-moss: primitive evergreen moss-like plant with spores in club-shaped strobiles
fern ally: pteridophytes of other classes than Filicopsida

club-moss (noun)	fern ally (noun)
primitive evergreen moss-like plant with spores in club-shaped strobiles	pteridophytes of other classes than Filicopsida