erythroderma vs skin disease

erythroderma and skin disease both are nouns.

Word	Noun	Adjective	Verb	Adverb
erythroderma	Yes	No	No	No
skin disease	Yes	No	No	No

As nouns, skin disease is a hypernym of erythroderma; that is, skin disease is a word with a broader meaning than erythroderma:

Other hypernyms of erythroderma include disease of the skin, skin disorder.

erythroderma (noun)	skin disease (noun)
any skin disorder involving abnormal redness	a disease affecting the skin