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 · Competitive PvP
A hero battle royale where teamwork and aim against human opponents decides fights.
Crazyracing Kartrider leans Execution (Pure Mechanics); My Hero Ultra Rumble leans Execution (Competitive PvP).
Crazyracing Kartrider leans a little harder on execution, though the gap is small.
Crazyracing Kartrider
Drift-boost timing and tight cornering define lap speed
My Hero Ultra Rumble
aim and combo timing in battles
My Hero Ultra Rumble leans a little harder on reads, though the gap is small.
Crazyracing Kartrider
Reading rival lines and item timing matters in PvP
My Hero Ultra Rumble
predicting human opponent tactics
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Crazyracing Kartrider
Item pickups add some randomness to races
My Hero Ultra Rumble
item and loot drops are random
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
My Hero Ultra Rumble
team comps and loadouts 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.