epitaph vs memorial

epitaph and memorial both are nouns.

Word	Noun	Adjective	Verb	Adverb
epitaph	Yes	No	No	No
memorial	Yes	No	No	No

As nouns, memorial is a hypernym of epitaph; that is, memorial is a word with a broader meaning than epitaph:

Other hypernyms of epitaph include commemoration, remembrance.

epitaph (noun)	memorial (noun)
an inscription on a tombstone or monument in memory of the person buried there	a structure erected to commemorate persons or events
a summary statement of commemoration for a dead person	a recognition of meritorious service
	a written statement of facts submitted in conjunction with a petition to an authority