account book vs leger

account book and leger both are nouns.

Word	Noun	Adjective	Verb	Adverb
account book	Yes	No	No	No
leger	Yes	No	No	No

As nouns, account book and leger are synonyms defined as:

account book and leger: a record in which commercial accounts are recorded

Other synonyms of account book include book, book of account, ledger.

account book (noun)	leger (noun)
a record in which commercial accounts are recorded	a record in which commercial accounts are recorded