Mass vs religious ceremony

Mass and religious ceremony both are nouns.

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

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

Mass: (Roman Catholic Church and Protestant Churches) the celebration of the Eucharist
religious ceremony: a ceremony having religious meaning

Other hypernyms of Mass include religious ritual.

Mass (noun)	religious ceremony (noun)
(Roman Catholic Church and Protestant Churches) the celebration of the Eucharist	a ceremony having religious meaning
a musical setting for a Mass
a sequence of prayers constituting the Christian Eucharistic rite