smoking gun vs evidence

smoking gun and evidence both are nouns.

Word	Noun	Adjective	Verb	Adverb
smoking gun	Yes	No	No	No
evidence	Yes	No	Yes	No

As nouns, evidence is a hypernym of smoking gun; that is, evidence is a word with a broader meaning than smoking gun:

smoking gun (noun)	evidence (noun)
indisputable evidence (especially of a crime)	your basis for belief or disbelief; knowledge on which to base belief
	(law) all the means by which any alleged matter of fact whose truth is investigated at judicial trial is established or disproved
	an indication that makes something evident

smoking gun (verb)	evidence (verb)
	provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes
	provide evidence for
	give evidence