In the Revenue Summary of the Revenue by Date(s) report. (Left Navigation > Reports & More > Reports > Search Reports: Revenue by Date(s) > Revenue Summary > Enter dates > Generate Report)
"Total Charges" is the cumulative total of charges for transactions marked with that payment method.
"$ Collected" is the total of all moneys received for those transactions marked with the payment method.
If there is a difference between the two, it is because only partial payments were received for some of these transactions. This is either due to existing credit on customers' accounts, that was applied to transactions, or because the customer paid partially and will pay the remaining balance later.