brain disorder vs brain disease

brain disorder and brain disease both are nouns.

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

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

Other synonyms of brain disorder include encephalopathy.

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