The main difference between billing and collection is that billing is invoicing customers for the goods or services they have received, while the collection process involves pursuing payments from customers who have not yet paid their outstanding invoices. Billing is often seen as a precursor to the collection, as it provides customers with a formal invoice detailing what they owe. On the other hand, collection is responsible for pursuing payments from customers who have failed to pay their bills. This can involve contacting them directly, issuing legal threats, or taking other measures to recover the money owed.