sacrament vs religious ceremony

sacrament and religious ceremony both are nouns.

Word	Noun	Adjective	Verb	Adverb
sacrament	Yes	No	No	No
religious ceremony	Yes	No	No	No

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

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
religious ceremony: a ceremony having religious meaning

Other hypernyms of sacrament include religious ritual.

sacrament (noun)	religious ceremony (noun)
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 ceremony having religious meaning