The copy of the sales invoice records the sales information, quantity, price and other important transaction details of the goods, and is an important financial voucher with legal effect. At the same time, sales invoices need to be audited and spot-checked by tax authorities, which can effectively avoid false invoicing and tax evasion.
A delivery document refers to a document filled in when goods are delivered out of the warehouse. It mainly records the name, quantity, specification and model of goods delivered out of the warehouse, and is an important record in warehouse management. The outbound order has no legal effect and is easy to be forged or tampered with, which is not as reliable as the copy of the sales invoice in proving the legitimacy and authenticity of the transaction.