epigraph vs citation

epigraph and citation both are nouns.

Word	Noun	Adjective	Verb	Adverb
epigraph	Yes	No	No	No
citation	Yes	No	No	No

As nouns, citation is a hypernym of epigraph; that is, citation is a word with a broader meaning than epigraph:

Other hypernyms of epigraph include quotation, quote.

epigraph (noun)	citation (noun)
an engraved inscription	an official award (as for bravery or service) usually given as formal public statement
a quotation at the beginning of some piece of writing	a short note recognizing a source of information or of a quoted passage
	a summons that commands the appearance of a party at a proceeding
	a passage or expression that is quoted or cited
	(law) the act of citing (as of spoken words or written passages or legal precedents etc.)