What is the Difference between an Order and an Invoice?

An order is a request for a product or service, while an invoice is a record of payment for that order (Receipt of payment). For a single order, multiple invoices can be created, each of which can include some or all of the purchased products. You can even generate print-ready PDF invoices as sales documents for your customers. Orders and Invoices have their own ID number and because it is possible to generate multiple invoices for a product, they may not match as it is incremental across the site. 

If an Order has products that ship, a shipment record can be generated when an order is invoiced or later.

To access the invoices you have created, go to Sales > Operations > Invoices on the Admin sidebar and open the Invoices grid.