I assume that you're working with a report.

Have you tried the following. Set up a group band on account#. Set up 2 variables:
1. TableTot -- which has the expression the sum of Total_from_Table and is reset at the beginning of the group.
2. CalcTot -- which has the expression the sum of Calculated_Total and is reset at the beginning of the group.

In the group band footer, put in 3 fields, with the variables TableTot, CalcTot and the expression TableTot - CalcTot.

If you need a grand total, follow a similar approach but have the differently named variables reset at report end.

Jay