This article defines invoice, sales receipt, bill, and statement so you can properly enter these transactions in QuickBooks Online.
An invoice is for when you want to collect funds from your customers.
A sales receipt is used for goods/services rendered at the time of a purchase (sometimes referred to as a "point of sale" purchase), or if your customers give you immediate payment.
A bill is used to describe transactions that are owed to vendors.
A statement is simply the status of the customer's account at a particular point in time.
For further information about the types of statements available, see How to create and manage statements.
Now you know the difference between an invoice, sales receipt, bill, and statement