There are three types of PDF documents that can be generated in DJ-Catalog2: vat invoice, proforma invoice, and the waybill. Those documents all look similar and contain a summary of the order, for example, seller information customer information, list of purchased products, date of sale, etc.
The difference comes, of course, from the purpose of those documents and at what occasion they are used. For example, by default Proforma invoice is delivered before the customer makes the payment, VAT invoice after making the payment, whereas the Waybill is not meant for the customer but used internally in the company.
Configuration
In the component settings, the Cart tab, you may enable/disable invoices, select whether they should be automatically sent to the customer, select the format of an invoice number and edit the "Seller" part of the invoice.
Underneath, in Shopping cart settings you can also select which order statuses should allow generating the VAT invoice. This is because by default every order is associated with Proforma.
All three types of documents can also be accessed from the list of orders page in the back-end:
