Standardisation
Invoices are different from receipts. Both Invoices and receipts are ways of tracking purchases of goods and services. In general the content of the invoices can be similar to that of receipts including tracking the amount of the sale, calculating sales tax owed and calculating any discounts applied to the purchase. Invoices differ from receipts in that invoices serve to notify customers of payments owed, whereas receipts serve as proof of completed payment.
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