spike moss vs lycopod

spike moss and lycopod both are nouns.

Word	Noun	Adjective	Verb	Adverb
spike moss	Yes	No	No	No
lycopod	Yes	No	No	No

As nouns, lycopod is a hypernym of spike moss; that is, lycopod is a word with a broader meaning than spike moss:

spike moss: any of numerous fern allies of the genus Selaginella
lycopod: primitive evergreen moss-like plant with spores in club-shaped strobiles

Other hypernyms of spike moss include club-moss, club moss.

spike moss (noun)	lycopod (noun)
any of numerous fern allies of the genus Selaginella	primitive evergreen moss-like plant with spores in club-shaped strobiles