head to head
Dirt 3 asks more than TrackMania United Forever, and the gap is variance.

Execution · Practiced Mastery
Precise rally car control over stages that reward memorisation and tuning.

Execution · Practiced Mastery
Pure time-trial racing testing relentless execution of an ever-more-optimised line.
Dirt 3 leans Execution (Practiced Mastery); TrackMania United Forever leans Execution (Practiced Mastery).
TrackMania United Forever leans a little harder on execution, though the gap is small.
Dirt 3
Car control on loose surfaces is a high physical ceiling
TrackMania United Forever
Frame-perfect lines over hundreds of restarts are everything
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Dirt 3
Racing the clock or scripted AI, nobody adapts
TrackMania United Forever
Time trials against ghosts - no one adapts to you
Dirt 3 leans clearly harder on variance.
Dirt 3
Surface conditions and minor physics noise per run
TrackMania United Forever
Deterministic physics with literally nothing hidden
TrackMania United Forever leans a little harder on optimization, though the gap is small.
Dirt 3
Stage knowledge and setup tuning reward study
TrackMania United Forever
Finding the theoretical fastest line is the meta-game
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.