What is the Difference Between Invoice and Bill?

People interchangeably use the terms invoice and bill when they want to refer to the document that computes transactions between a seller and a buyer. However, they are different. A seller might have to create both an invoice and bill as proof of the transaction. Consider a restaurant management software or a billing system. When someone places an order at the restaurant, they create an order with items and print a KOT (Kitchen Order Ticket). After the order is served, the restaurant reviews the order and generates an invoice.