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
A rally racer where mastering precise car control against tricky terrain is everything.

Execution · Pure Mechanics
A tilt-control balance game about rolling precisely through floating mazes.
Colin McRae: Dirt 2 leans Execution (Pure Mechanics); Super Monkey Ball 3D leans Execution (Pure Mechanics).
Super Monkey Ball 3D leans a little harder on execution, though the gap is small.
Colin McRae: Dirt 2
precise rally driving and braking required
Super Monkey Ball 3D
Precise tilt control under gravity is the entire test
Super Monkey Ball 3D leans a little harder on reads, though the gap is small.
Colin McRae: Dirt 2
no adaptive opponents, mostly time trials
Super Monkey Ball 3D
Solo stages, no opponent to predict
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Colin McRae: Dirt 2
weather and surface conditions vary
Super Monkey Ball 3D
Levels are fixed with little randomness
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
Super Monkey Ball 3D
Optimal lines through mazes reward route learning
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.