The WHMCS-supplied PayPal Pro Reference Payments module only supports credit cards - the only difference from typical credit card processing modules is that it stores the full card number at PayPal and WHMCS itself stores only a PayPal-supplied token. Whereas our module supports PayPal Billing Agreements, which not only allows for automatic recurring payment processing (same as credit cards do), it also allows the client to use any payment method on their PayPal account, including bank accounts and their PayPal account balance.
