head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Execution · Pure Mechanics
A rally racer where mastering precise car control against tricky terrain is everything.

Execution · Pure Mechanics
Hitting braking points and managing weight transfer lap after deterministic lap.
Colin McRae: Dirt 2 leans Execution (Pure Mechanics); Need for Speed: Shift 2 Unleashed leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Colin McRae: Dirt 2
precise rally driving and braking required
Need for Speed: Shift 2 Unleashed
Braking points and weight transfer control define lap times
Need for Speed: Shift 2 Unleashed leans a little harder on reads, though the gap is small.
Colin McRae: Dirt 2
no adaptive opponents, mostly time trials
Need for Speed: Shift 2 Unleashed
AI drivers follow racing lines, humans rarely adapt deeply
Colin McRae: Dirt 2 leans a little harder on variance, though the gap is small.
Colin McRae: Dirt 2
weather and surface conditions vary
Need for Speed: Shift 2 Unleashed
Deterministic physics - the track never changes
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Colin McRae: Dirt 2
car tuning and racing lines solvable
Need for Speed: Shift 2 Unleashed
Car setup tuning and line study underpin pace
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.