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

Execution · Pure Mechanics
Throttle and counter-steer precision on loose surfaces against the clock.

Execution · Pure Mechanics
Precise jump execution across fixed levels with secrets to memorise.
Colin McRae: Dirt leans Execution (Pure Mechanics); Super Mario World leans Execution (Pure Mechanics).
Colin McRae: Dirt leans a little harder on execution, though the gap is small.
Colin McRae: Dirt
Car control on loose surfaces is the entire test
Super Mario World
Perfect inputs trivialise every jump, spin and cape flight
Colin McRae: Dirt leans a little harder on reads, though the gap is small.
Colin McRae: Dirt
Racing the clock or AI lines, nothing adapts
Super Mario World
Scripted Koopas adapt to nothing
Colin McRae: Dirt leans a little harder on variance, though the gap is small.
Colin McRae: Dirt
Surface grip and damage add mild run noise
Super Mario World
Levels are fixed; nothing hidden survives one playthrough
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Colin McRae: Dirt
Setup tuning and corner-line knowledge underpin pace
Super Mario World
Secret exits and route knowledge add a modest solvable layer
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.