breviary vs prayerbook

breviary and prayerbook both are nouns.

Word	Noun	Adjective	Verb	Adverb
breviary	Yes	No	No	No
prayerbook	Yes	No	No	No

As nouns, prayerbook is a hypernym of breviary; that is, prayerbook is a word with a broader meaning than breviary:

breviary: (Roman Catholic Church) a book of prayers to be recited daily by certain priests and members of religious orders
prayerbook: a book containing prayers

Other hypernyms of breviary include prayer book.

breviary (noun)	prayerbook (noun)
(Roman Catholic Church) a book of prayers to be recited daily by certain priests and members of religious orders	a book containing prayers