different between pocketbook vs billfold

English

From pocket +? book, popularized in its sense as a paperback by the success of Pocket Books in the United States after its 1939 launch.

pocketbook (plural pocketbooks)

(US) A woman's purse.
(dated) A wallet for paper money.
(figuratively) One's personal budget or economic capacity - the amount one can afford.
(uncommon) A small book, particularly (US) a paperback or (Britain) notebook able to fit into a pocket.

bill +? fold

billfold (plural billfolds)

A small, folding sleeve or case designed to hold paper currency, as well as credit cards, pictures, etc.
Bill had so many pictures of his family stuffed into his billfold that it barely fit into his pocket.