calf's brain vs brain

calf's brain and brain both are nouns.

Word	Noun	Adjective	Verb	Adverb
calf's brain	Yes	No	No	No
brain	Yes	No	Yes	No

As nouns, brain is a hypernym of calf's brain; that is, brain is a word with a broader meaning than calf's brain:

calf's brain (noun)	brain (noun)
the brain of a calf eaten as meat	that part of the central nervous system that includes all the higher nervous centers; enclosed within the skull; continuous with the spinal cord
	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

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