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

Execution · Practiced Mastery
A kart racer with an adventure structure and three vehicle types, lighter on item chaos than its rivals.

Execution · Pure Mechanics
A gothic kart racer testing drift execution and track knowledge with item chaos.
Diddy Kong Racing leans Execution (Practiced Mastery); Nightmare Kart leans Execution (Pure Mechanics).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Diddy Kong Racing
Drift boosts across car, hovercraft and plane demand precision.
Nightmare Kart
Drift lines and combat aim decide races
Nightmare Kart leans a little harder on reads, though the gap is small.
Diddy Kong Racing
Multiplayer item duels add mild prediction; AI is scripted.
Nightmare Kart
Human racers in versus add mild prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Diddy Kong Racing
Balloon pickups and items inject moderate randomness.
Nightmare Kart
Item pickups inject kart-racer chaos
Diddy Kong Racing leans a little harder on optimization, though the gap is small.
Diddy Kong Racing
Vehicle choice, balloon upgrade routes and boss strategies converge.
Nightmare Kart
Track knowledge and boss patterns are learnable
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.