poison sumac vs Rhus dermatitis

poison sumac and Rhus dermatitis both are nouns.

Word	Noun	Adjective	Verb	Adverb
poison sumac	Yes	No	No	No
Rhus dermatitis	Yes	No	No	No

As nouns, Rhus dermatitis is a hypernym of poison sumac; that is, Rhus dermatitis is a word with a broader meaning than poison sumac:

poison sumac: dermatitis resulting from contact with a poison sumac plant
Rhus dermatitis: contact dermatitis resulting from contact with plants of the genus Toxicodendron

poison sumac (noun)	Rhus dermatitis (noun)
smooth American swamp shrub with pinnate leaves and greenish flowers followed by greenish white berries; yields an irritating oil	contact dermatitis resulting from contact with plants of the genus Toxicodendron
dermatitis resulting from contact with a poison sumac plant