extreme unction vs last rites

extreme unction and last rites both are nouns.

Word	Noun	Adjective	Verb	Adverb
extreme unction	Yes	No	No	No
last rites	Yes	No	No	No

As nouns, extreme unction and last rites are synonyms defined as:

extreme unction and last rites: a Catholic sacrament; a priest anoints a dying person with oil and prays for salvation

Other synonyms of extreme unction include anointing of the sick.

extreme unction (noun)	last rites (noun)
a Catholic sacrament; a priest anoints a dying person with oil and prays for salvation	rites performed in connection with a death or burial
	a Catholic sacrament; a priest anoints a dying person with oil and prays for salvation