disease of the skin vs skin disease

disease of the skin and skin disease both are nouns.

Word	Noun	Adjective	Verb	Adverb
disease of the skin	Yes	No	No	No
skin disease	Yes	No	No	No

As nouns, disease of the skin and skin disease are synonyms defined as:

Other synonyms of disease of the skin include skin disorder.

disease of the skin (noun)	skin disease (noun)
a disease affecting the skin	a disease affecting the skin