Seems pretty clear to me, about the same length trips, one at low speed (stop and go), one slightly longer at higher speed (mostly freeway).
Mapquest ( http://www.mapquest.com/ ) has a handy tool you can use to estimate your fuel cost. You just enter your average MPGs and the current cost of fuel.
Too many unknowns.
Terrain?
Road conditions?
Traffic?
Types of routes (city vs highway)?
Type of vehicle…Prius, Previa, or Lambo? The Cf coefficients, HP, and drivetrains are very different, and this would have an effect IF the terrains were dramatically different, like one highway and the other through town or on dusty country roads.
In any case, over a trip that short the difference would be within the range of normal measurement error.