Agnus Dei vs prayer

Agnus Dei and prayer both are nouns.

Word	Noun	Adjective	Verb	Adverb
Agnus Dei	Yes	No	No	No
prayer	Yes	No	No	No

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

Agnus Dei (noun)	prayer (noun)
figure of a lamb; emblematic of Christ	the act of communicating with a deity (especially as a petition or in adoration or contrition or thanksgiving)
a liturgical prayer beginning with these Latin words	earnest or urgent request
	a fixed text used in praying
	reverent petition to a deity
	someone who prays to God