potato mildew vs potato disease

potato mildew and potato disease both are nouns.

Word	Noun	Adjective	Verb	Adverb
potato mildew	Yes	No	No	No
potato disease	Yes	No	No	No

As nouns, potato mildew and potato disease are synonyms defined as:

Other synonyms of potato mildew include potato blight, potato mold, potato murrain.

potato mildew (noun)	potato disease (noun)
a blight of potatoes	a blight of potatoes