Difference between Invoice and bill

An invoice is a commercial document issued by a seller to a buyer, indicating the products, quantities and agreed prices for products or services that the Seller has already provided the Buyer with. An invoice indicates that, unless paid in advance, payment is due by the buyer to the seller, according to the agreed terms.

A bill is a document requesting payment for goods previously supplied. This presentation of a bill is common practice on the part of restaurants, credit card companies, utilities, and other service providers. The bill for something is the total price of all services and goods received but not yet paid for, and is presented in the expectation of immediate payment in full. If a bill is not paid, a collections company is usually given the responsibility of collecting the amount due and service is terminated. Under English law, a person who makes off without paying the bill, or who dishonestly secures a remission in the amount payable, commits an offence under the Theft Act 1978. When a company cannot pay its bills, it is said to be insolvent.

These two words are generally used interchangeable

You can also see the dictionery meaning by follow the following links.

https://www.wordreference.com/definition/invoice.htm

https://www.wordreference.com/definition/bill.htm?v=b