There are two ways to answer this question. From a work-flow point of view, bill batches are created prior to invoicing. From a conceptual point of view, bill batches and invoices serve two different purposes. Bill batches are used to track and mark which items needs to be billed to the client. They help the administrator responsible for billing.

Invoices, on the other hand, are the nicely formatted report you present to the client when you request payment.

Most everyone will want to create bill batches in EnterYourHours.com, but some administrators might choose to use another accounting package to create your invoices.