Hi,

A Pro-forma invoice is a forecasted document before the final bill is issued. Pro-forma is prepared based on the cost mentioned in a sales order. This defines the promise of a vendor to deliver the goods or services at a given price as advised to the buyer.

The invoice should outline the goods or services provided and the total price as well as VAT (if applicable), along with any discounts that have been applied. 

A quotation, on the other hand, is issued before the goods or services are delivered and provides an itemised list and expected costs.

Regards