AccountsKeeping - Online Bookkeeping

You can use Statements in Quickbooks if you bill your customers over a regular period of time and the customer may not be paying immediately on every sale. It's essentially one kind of an outstanding statement of you customers that they may owe to you. We won't be needing this feature.

Progress Invoicing is useful for contractors, legal attorneys and such people where the service or product is going to be provided over a period of time and reciprocally the payments are going to be made by the customer at regular intervals or "milestones" have been predefined. So you will be keeping track of your regular billing according to the agreed schedules and progress of the work.
We will not be needing this feature for our example.