AR invoice is a document sent to the customer with details like, Bill-to customer
code, product code, qty sent, price, currency, credit terms, tax details,etc. Based
on this invoice, customer will make payment to the company and the same is applied
against the invoice.
AP invoice is the document received from the supplier and contains informations
such supplier details, product code, qty, price and tax details. This invoice is
entered in the AP module and payment is made to the supplier against this invoice.