head to head
Mario Kart 8 asks more than Sonic Forces: Speed Battle, 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 mobile racing runner testing reflex lane-play under item RNG and upgrade grind.
Mario Kart 8 leans Execution (Twitch Chaos); Sonic Forces: Speed Battle 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
Sonic Forces: Speed Battle
Lane-switch timing and trap dodging decide races
Sonic Forces: Speed Battle leans a little harder on reads, though the gap is small.
Mario Kart 8
minimal, mostly reacting not predicting
Sonic Forces: Speed Battle
Live opponents exist but interaction is mostly indirect items
Mario Kart 8 leans clearly harder on variance.
Mario Kart 8
item boxes are heavily randomized
Sonic Forces: Speed Battle
Item rolls and character gacha swing outcomes
Mario Kart 8 leans a little harder on optimization, though the gap is small.
Mario Kart 8
track lines and item strategy solvable
Sonic Forces: Speed Battle
Character upgrades and route knowledge compound over time
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.