head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

Execution · Twitch Chaos
Kart-racing control with item RNG swinging family-friendly races.

Execution · Twitch Chaos
N64 couch classic where blue shells and shortcuts decide friendships.
F1 Race Stars leans Execution (Twitch Chaos); Mario Kart 64 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.
F1 Race Stars
Kart handling and boost timing decide clean laps
Mario Kart 64
Mini-turbo snaking and shortcut execution
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
F1 Race Stars
Human racers feint and time item attacks in multiplayer
Mario Kart 64
Couch rivals bait shells and fakes
Mario Kart 64 leans a little harder on variance, though the gap is small.
F1 Race Stars
Item rolls swing positions like any kart racer
Mario Kart 64
Item draws swing every race
Mario Kart 64 leans a little harder on optimization, though the gap is small.
F1 Race Stars
Track shortcuts and KERS timing are learnable edges
Mario Kart 64
Shortcut and line knowledge is fully mapped
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.