brain disease vs brain disorder

brain disease and brain disorder both are nouns.

Word	Noun	Adjective	Verb	Adverb
brain disease	Yes	No	No	No
brain disorder	Yes	No	No	No

As nouns, brain disease and brain disorder are synonyms defined as:

Other synonyms of brain disease include encephalopathy.

brain disease (noun)	brain disorder (noun)
any disorder or disease of the brain	any disorder or disease of the brain