Mass vs prayer

Mass and prayer both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mass	Yes	No	No	No
prayer	Yes	No	No	No

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

Mass (noun)	prayer (noun)
(Roman Catholic Church and Protestant Churches) the celebration of the Eucharist	the act of communicating with a deity (especially as a petition or in adoration or contrition or thanksgiving)
a musical setting for a Mass	earnest or urgent request
a sequence of prayers constituting the Christian Eucharistic rite	a fixed text used in praying
	reverent petition to a deity
	someone who prays to God