head to head
Neither is simply harder - they are hard in different places. Chocobo Racing demands more reads; Mario Kart 8 demands more variance.

Execution · Twitch Chaos
A kart racer testing drift execution under item-roll variance.

Execution · Twitch Chaos
A kart racer where controlled chaos from random items tempers otherwise precise driving skill.
Chocobo Racing leans Execution (Twitch Chaos); Mario Kart 8 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.
Chocobo Racing
Drift timing and item dodges decide close finishes
Mario Kart 8
precise drifting and item timing matter
Chocobo Racing leans clearly harder on reads.
Chocobo Racing
Two-player races add light human prediction
Mario Kart 8
minimal, mostly reacting not predicting
Mario Kart 8 leans clearly harder on variance.
Chocobo Racing
Item rolls swing race outcomes kart-style
Mario Kart 8
item boxes are heavily randomized
Mario Kart 8 leans a little harder on optimization, though the gap is small.
Chocobo Racing
Ability picks and track shortcuts reward study
Mario Kart 8
track lines and item strategy 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.