A work order is an official document that initiates a task or job and outlines the scope of work that needs to be completed for it. It is typically used by businesses to keep track of expenses associated with their projects and clients, as well as to ensure the highest quality of work. An invoice, on the other hand, is a billing document that itemizes services performed or goods sold. Invoices are sent after services have been rendered or goods exchanged, and they outline how payment should be made and when it is due. By understanding the difference between a work order and an invoice, businesses can better manage their finances, ensure high-quality services and products, and keep customers satisfied.