Lots of things go into vehicle tuning....
I have not heard of any major internal differences between teh Jeeps and the 300C variations... but I would fully expect tuning differences.
The cars are going to be tuned for a more sporty higher reving feel and shifts, whereas a $45k Jeep is going to be tuned for some level of smoothness, but also torque to pull more load, tow etc. Not to mention different packaging constraints for intake/exhaust/cooling etc.
As far as factory vs measured hp #s? Factor test is 'bench' horsepower if you will. SAE certified testing conditions, but with accessories, exhaust etc... Dyno numbers are power measured after parasitic losses in the driveline (torque convert, trans, differential, etc etc) and often depend on teh equipment used to measure (dynojets vs Mustang, entered load parameters etc on the dyno setup)
So yeah... Only real way to know is find a Chrysler powertrain Engineer.