daybook vs book of account

daybook and book of account both are nouns.

Word	Noun	Adjective	Verb	Adverb
daybook	Yes	No	No	No
book of account	Yes	No	No	No

As nouns, book of account is a hypernym of daybook; that is, book of account is a word with a broader meaning than daybook:

Other hypernyms of daybook include account book, book, ledger, leger.

daybook (noun)	book of account (noun)
an accounting journal as a physical object	a record in which commercial accounts are recorded
a ledger in which transactions have been recorded as they occurred