brain disease vs encephalopathy

brain disease and encephalopathy both are nouns.

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

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

Other synonyms of brain disease include brain disorder.

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