An invoice requests payment
An invoice describes the work or goods, the amount due and when to pay. It is normally sent as part of the billing process and can be outstanding until the payment is received.
A receipt acknowledges payment
A receipt records a payment already received. Include the date, amount, payer and payment method. Reference the invoice number when the receipt relates to an earlier invoice.
Example: a completed design project
You send invoice INV-024 for a completed design milestone. After verifying the customer’s payment, you issue receipt REC-019 with INV-024 in its notes. Keep both records; creating a receipt in this tool does not update an invoice automatically.