rose moss vs portulaca

rose moss and portulaca both are nouns.

Word	Noun	Adjective	Verb	Adverb
rose moss	Yes	No	No	No
portulaca	Yes	No	No	No

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

rose moss: widely cultivated in many varieties for its fleshy moss-like foliage and profusion of brightly colored flowers
portulaca: a plant of the genus Portulaca having pink or red or purple or white ephemeral flowers

rose moss (noun)	portulaca (noun)
widely cultivated in many varieties for its fleshy moss-like foliage and profusion of brightly colored flowers	a plant of the genus Portulaca having pink or red or purple or white ephemeral flowers