head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Twitch Chaos
Kart racing where driving skill fights a steady drizzle of random gag items.

Execution · Twitch Chaos
Kart racing execution moderated by item randomness and learnable track routes.
Looney Tunes: Space Race leans Execution (Twitch Chaos); Sonic & All-Stars Racing Transformed 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.
Looney Tunes: Space Race
Racing lines and drift control still decide most finishes
Sonic & All-Stars Racing Transformed
Drift timing and transforming vehicle control reward practice
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Looney Tunes: Space Race
Light gag-timing duels against human racers
Sonic & All-Stars Racing Transformed
Human racers add light positional mind games
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Looney Tunes: Space Race
Random gag pickups scramble race outcomes
Sonic & All-Stars Racing Transformed
Item rolls regularly upend race positions
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Looney Tunes: Space Race
Shortcut and track knowledge compound every lap
Sonic & All-Stars Racing Transformed
Track shortcuts and drift-boost routes are learnable
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.