mother-of-thousands vs genus Saxifraga

mother-of-thousands and genus Saxifraga both are nouns.

Word	Noun	Adjective	Verb	Adverb
mother-of-thousands	Yes	No	No	No
genus Saxifraga	Yes	No	No	No

mother-of-thousands (noun)	genus Saxifraga (noun)
eastern Asiatic saxifrage with racemes of small red-and-white flowers; spreads by numerous creeping stolons	type genus of the Saxifragaceae; large genus of usually perennial herbs of Arctic and cool regions of Northern Hemisphere: saxifrage