People mix these up because both list money and items. They serve different moments in the job.
Invoice
You send an invoice when payment is still due. It has a due date, an amount due, and how to pay. That is the document InvoiceBizz creates.
Receipt
You send a receipt after the money has arrived. It should say paid, the date paid, and the amount received. InvoiceBizz does not issue receipts. If a client needs one, send a short note or a copy of the paid invoice marked paid in your own records.
Why the difference matters
A client who files an unpaid invoice as a receipt may think they already paid. A client who gets a receipt before they paid may dispute the amount later. Use what an invoice is when you are billing, then keep your own proof of payment.
Build the bill in the online invoice generator, download the PDF, and send it before you mark anything as paid.