efflorescence vs hives

efflorescence and hives both are nouns.

Word	Noun	Adjective	Verb	Adverb
efflorescence	Yes	No	No	No
hives	Yes	No	No	No

As nouns, hives is a hyponym of efflorescence; that is, hives is a word with a more specific, narrower meaning than efflorescence:

efflorescence: any red eruption of the skin
hives: an itchy skin eruption characterized by weals with pale interiors and well-defined red margins; usually the result of an allergic response to insect bites or food or drugs

Other hyponyms of efflorescence include heat rash, miliaria, prickly heat, nettle rash, urticaria, urtication.

efflorescence (noun)	hives (noun)
a powdery deposit on a surface	an itchy skin eruption characterized by weals with pale interiors and well-defined red margins; usually the result of an allergic response to insect bites or food or drugs
the time and process of budding and unfolding of blossoms
any red eruption of the skin
the period of greatest prosperity or productivity