lycopod vs spike moss

lycopod and spike moss both are nouns.

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

As nouns, spike moss is a hyponym of lycopod; that is, spike moss is a word with a more specific, narrower meaning than lycopod:

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

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