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 · Twitch Chaos
A kart racer where controlled chaos from random items tempers otherwise precise driving skill.

Execution · Twitch Chaos
An item-based kart racer testing driving precision against item chaos.
Mario Kart 8 leans Execution (Twitch Chaos); Nickelodeon Kart Racers 2: Grand Prix leans Execution (Twitch Chaos).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Mario Kart 8
precise drifting and item timing matter
Nickelodeon Kart Racers 2: Grand Prix
Drifting, boost timing and cornering need accuracy
Nickelodeon Kart Racers 2: Grand Prix leans a little harder on reads, though the gap is small.
Mario Kart 8
minimal, mostly reacting not predicting
Nickelodeon Kart Racers 2: Grand Prix
AI racers scripted; light multiplayer adaptation
Mario Kart 8 leans a little harder on variance, though the gap is small.
Mario Kart 8
item boxes are heavily randomized
Nickelodeon Kart Racers 2: Grand Prix
Pickup items and rubber-banding inject chaos
Mario Kart 8 leans a little harder on optimization, though the gap is small.
Mario Kart 8
track lines and item strategy solvable
Nickelodeon Kart Racers 2: Grand Prix
Crew builds, kart tuning and racing lines matter
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.