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 competitive kart racer testing drift-boost execution against human rivals.

Execution · Practiced Mastery
The sequel adding Horde mode to the campaign-plus-versus cover shooter formula.
Crazyracing Kartrider leans Execution (Pure Mechanics); Gears of War 2 leans Execution (Practiced Mastery).
Crazyracing Kartrider leans a little harder on execution, though the gap is small.
Crazyracing Kartrider
Drift-boost timing and tight cornering define lap speed
Gears of War 2
Gnasher battles and movement tech set the ceiling
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Crazyracing Kartrider
Reading rival lines and item timing matters in PvP
Gears of War 2
Human opponents in versus drive prediction play
Crazyracing Kartrider leans a little harder on variance, though the gap is small.
Crazyracing Kartrider
Item pickups add some randomness to races
Gears of War 2
Horde spawns add mild randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Crazyracing Kartrider
Track lines, drift chaining, and item usage are solvable
Gears of War 2
Power-weapon timing and positioning are solvable
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.