An invoice number is a number assigned to uniquely identify invoices. It generally appears near the top of the invoice document so it can be easily noted by both the recipient of the invoice and the business providing it.
No, a receipt number and invoice number are not the same. An invoice number is a unique sequential number, created right when a purchase is made. While a receipt number is generated only when payment for that invoice has been fully made. Both of these numbers are identifiers that help track payments.