@kami_kara, see my answer on the other thread where you asked the same questions:
It also appears you are confusing receipts, invoices, and statements. A receipt documents an immediate transaction in which money changes hands. An invoice creates an obligation for a customer to pay a supplier. This can be your customer owing you money on a sales invoice or you owning your supplier on a purchase invoice. Statements are summary reports of invoices and/or transactions on a particular customer’s account over a defined period or including all unpaid invoices.