prayerbook vs missal

prayerbook and missal both are nouns.

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

As nouns, missal is a hyponym of prayerbook; that is, missal is a word with a more specific, narrower meaning than prayerbook:

prayerbook: a book containing prayers
missal: (Roman Catholic Church) a book containing all the prayers and responses needed to celebrate Mass throughout the year

Other hyponyms of prayerbook include breviary, Book of Psalms, Psalter.

prayerbook (noun)	missal (noun)
a book containing prayers	(Roman Catholic Church) a book containing all the prayers and responses needed to celebrate Mass throughout the year