Quote: This is a quote for a parts sale.

Pro Forma Invoice: This is a quote for a customer who has an address located outside the United States.

Sales Order: This is when you print out a sales order before payment has been received.

Sales Receipt: This is when you print out a sales order that has received payment from any payment method except "Account".

Invoice: This is when you print out a sales order that was charged to the customer's account.