monument vs sepulture

monument and sepulture both are nouns.

Word	Noun	Adjective	Verb	Adverb
monument	Yes	No	No	No
sepulture	Yes	No	No	No

As nouns, sepulture is a hypernym of monument; that is, sepulture is a word with a broader meaning than monument:

Other hypernyms of monument include burial chamber, sepulcher, sepulchre.

monument (noun)	sepulture (noun)
a structure erected to commemorate persons or events	a chamber that is used as a grave
a burial vault (usually for some famous person)	the ritual placing of a corpse in a grave
an important site that is marked and preserved as public property