Greetings, @scott-allan,
The Purchases report is consist of your purchases and open POs from each supplier. While, the Transaction List and Expenses reports list all vendors and customers transactions.
To learn more on how to customise reports in QuickBooks Online, feel free to read through here: How to customise reports.
Please don't hesitate to let me know if there's anything you'd like to know about your reports. Just leave a comment below and I'd be glad to answer.
