brain vs brain stem

brain and brain stem both are nouns.

Word	Noun	Adjective	Verb	Adverb
brain	Yes	No	Yes	No
brain stem	Yes	No	No	No

brain (noun)	brain stem (noun)
that part of the central nervous system that includes all the higher nervous centers; enclosed within the skull; continuous with the spinal cord	the part of the brain continuous with the spinal cord and comprising the medulla oblongata and pons and midbrain and parts of the hypothalamus
mental ability
that which is responsible for one's thoughts, feelings, and conscious brain functions; the seat of the faculty of reason
the brain of certain animals used as meat
someone who has exceptional intellectual ability and originality

brain (verb)	brain stem (verb)
hit on the head
kill by smashing someone's skull