head to head
Mario Kart 8 asks more than Mario & Sonic at the Olympic Games Tokyo 2020, 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
A party collection of timing minigames designed to keep everyone competitive.
Mario Kart 8 leans Execution (Twitch Chaos); Mario & Sonic at the Olympic Games Tokyo 2020 leans Execution (Twitch Chaos).
Mario Kart 8 leans a little harder on execution, though the gap is small.
Mario Kart 8
precise drifting and item timing matter
Mario & Sonic at the Olympic Games Tokyo 2020
Button-timing and waggle minigames are the core test
Mario & Sonic at the Olympic Games Tokyo 2020 leans a little harder on reads, though the gap is small.
Mario Kart 8
minimal, mostly reacting not predicting
Mario & Sonic at the Olympic Games Tokyo 2020
Light couch-PvP guessing in some head-to-head events
Mario Kart 8 leans clearly harder on variance.
Mario Kart 8
item boxes are heavily randomized
Mario & Sonic at the Olympic Games Tokyo 2020
Event RNG and party chaos level the field
Mario Kart 8 leans clearly harder on optimization.
Mario Kart 8
track lines and item strategy solvable
Mario & Sonic at the Olympic Games Tokyo 2020
Each event has a shallow optimal technique to learn
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.