The Comparison Report lists the total mileage, cost and time estimates for all open routes. To create this report, select the Routes tab > Comparison Report or press F4 on your keyboard when two or more generated routes are active.    

Columns from left to right show trip totals for miles, estimated cost, estimated hours, toll costs (if the Tolls add-on is installed and toll calculation is turned on), estimated fuel cost, estimated cost of labor, estimated miscellaneous costs, and estimated greenhouse gas emission (these last four columns are not shown in the resized report window below). Values that affect cost, time, toll and greenhouse gas estimates are set in the File menu > Application Settings > Route Costs. 

The Comparison Report lists only the origin and destination of each route. If there are stop-off points in one route and no stop-offs in another, the mileage discrepancy between these routes could be large. Check the stops in the route window if you see differences in mileage that are larger than expected.