head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
Pioneering six-degrees-of-freedom shooter through robot-infested mines.

Execution · Practiced Mastery
Precise rally car control over stages that reward memorisation and tuning.
Descent leans Execution (Practiced Mastery); Dirt 3 leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Descent
Full 6DOF control and aim under disorientation is the test
Dirt 3
Car control on loose surfaces is a high physical ceiling
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Descent
Scripted robot behaviors, no adaptation
Dirt 3
Racing the clock or scripted AI, nobody adapts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Descent
Mine layouts fixed; ambushes surprise only once
Dirt 3
Surface conditions and minor physics noise per run
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Descent
Route memorization and weapon economy reward optimization
Dirt 3
Stage knowledge and setup tuning reward study
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.