I've got a way how you can compare your invoices to sales receipts, elismaniemann-pe.
You can't match invoices with sales receipts since both are sales transactions. But you can compare them.
You can pull up a Transaction List by Customer report and customise it to Invoice transaction type, then run another one for Sales receipts. This way, you can easily compare the two.
Here's how:
Go to the Reports tab.
From the Sales and customers section, select Transaction List by Customer.
Click Customise.
Click Filter and choose Invoice from the Transaction Type.
Click on Run report.
Repeat another step for the Sales receipts to get the data needed.