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