last rites vs sacrament

last rites and sacrament both are nouns.

Word	Noun	Adjective	Verb	Adverb
last rites	Yes	No	No	No
sacrament	Yes	No	No	No

As nouns, sacrament is a hypernym of last rites; that is, sacrament is a word with a broader meaning than last rites:

last rites: a Catholic sacrament; a priest anoints a dying person with oil and prays for salvation
sacrament: a formal religious ceremony conferring a specific grace on those who receive it; the two Protestant ceremonies are baptism and the Lord's Supper; in the Roman Catholic Church and the Eastern Orthodox Church there are seven traditional rites accepted as instituted by Jesus: baptism and confirmation and Holy Eucharist and penance and holy orders and matrimony and extreme unction

last rites (noun)	sacrament (noun)
rites performed in connection with a death or burial	a formal religious ceremony conferring a specific grace on those who receive it; the two Protestant ceremonies are baptism and the Lord's Supper; in the Roman Catholic Church and the Eastern Orthodox Church there are seven traditional rites accepted as instituted by Jesus: baptism and confirmation and Holy Eucharist and penance and holy orders and matrimony and extreme unction
a Catholic sacrament; a priest anoints a dying person with oil and prays for salvation