A Credit Note or Credit Memo is a document issued by a seller to a buyer. The seller issues a Credit Note for the same or lower amount than the invoice, and then repays the money to the buyer or sets it off against a balance due from other transactions.

A Credit Note is a document used to adjust or rectify errors made in a sales invoice which has already been sent to a customer.

Also a Credit Note can be a document from a bank to a depositor to indicate the depositor's balance is being increased because of an event other than a deposit.

A Debit Note is issued by a customer to a supplier as a means of formally requesting a credit note. a supplier might also issue a debit note instead of an invoice in order to adjust upwards the amount of an invoice already issued (as if the invoice is recorded in wrong value)

A Debit note are document that provide a debtor with information regarding an outstanding debt. A debit note is issued by the lender or creditor and serves as either notification of a debt that will be invoiced shortly or a reminder of a debt that was previously invoiced and is currently outstanding. While an invoice is also an official notification of a debt owed, it is not considered to be a debit note.

A Delivery note is document accompanying a shipment of goods that lists the description, grade, and quantity of the goods delivered. A copy of the delivery note, signed by the buyer or consignee, is returned to the seller or consignor as a proof of delivery.

In short a delivery note is a document showing that goods have been delivered. Seller fills the delivery note. Buyer on delivery checks the delivery note. In case of deviations, delivery is rejected.