head to head
Mario Kart 8 asks more than Zombie Tsunami, and the gap is variance.

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

Execution · Twitch Chaos
One-touch reflex timing against procedurally generated obstacle streams.
Mario Kart 8 leans Execution (Twitch Chaos); Zombie Tsunami 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
Zombie Tsunami
One-touch jump timing for a growing horde is the whole test
Mario Kart 8 leans a little harder on reads, though the gap is small.
Mario Kart 8
minimal, mostly reacting not predicting
Zombie Tsunami
No opponent - obstacles are procedural
Mario Kart 8 leans clearly harder on variance.
Mario Kart 8
item boxes are heavily randomized
Zombie Tsunami
Procedural level generation decides what each run offers
Mario Kart 8 leans clearly harder on optimization.
Mario Kart 8
track lines and item strategy solvable
Zombie Tsunami
Upgrade spending is a thin meta layer
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.