keratosis vs skin disease

keratosis and skin disease both are nouns.

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

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

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

keratosis (noun)	skin disease (noun)
a skin condition marked by an overgrowth of layers of horny skin	a disease affecting the skin