rock geranium vs alumbloom

rock geranium and alumbloom both are nouns.

Word	Noun	Adjective	Verb	Adverb
rock geranium	Yes	No	No	No
alumbloom	Yes	No	No	No

As nouns, alumbloom is a hypernym of rock geranium; that is, alumbloom is a word with a broader meaning than rock geranium:

rock geranium: plant with basal leaves mottled with white and flowers in lax panicles on erect stems
alumbloom: any of several herbs of the genus Heuchera

Other hypernyms of rock geranium include alumroot.

rock geranium (noun)	alumbloom (noun)
plant with basal leaves mottled with white and flowers in lax panicles on erect stems	any of several herbs of the genus Heuchera