sanity vs reason

sanity and reason both are nouns.

Word	Noun	Adjective	Verb	Adverb
sanity	Yes	No	No	No
reason	Yes	No	Yes	No

As nouns, reason is a hyponym of sanity; that is, reason is a word with a more specific, narrower meaning than sanity:

Other hyponyms of sanity include lucidity, rationality, reasonableness.

sanity (noun)	reason (noun)
normal or sound powers of mind	the capacity for rational thought or inference or discrimination
	a fact that logically justifies some premise or conclusion
	a justification for something existing or happening
	an explanation of the cause of some phenomenon
	a rational motive for a belief or action
	the state of having good sense and sound judgment

sanity (verb)	reason (verb)
	think logically
	decide by reasoning; draw or come to a conclusion
	present reasons and arguments