inhumation vs entombment

inhumation and entombment both are nouns.

Word	Noun	Adjective	Verb	Adverb
inhumation	Yes	No	No	No
entombment	Yes	No	No	No

As nouns, inhumation and entombment are synonyms defined as:

Other synonyms of inhumation include burial, interment, sepulture.

inhumation (noun)	entombment (noun)
the ritual placing of a corpse in a grave	the ritual placing of a corpse in a grave