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

Execution · Practiced Mastery
Tests arcade sports timing in a licensed fantasy sport with swingy Snitch catches.

Execution · Twitch Chaos
Sloppy kart handling where random items swing races more than driving skill.
Harry Potter: Quidditch World Cup leans Execution (Practiced Mastery); South Park Rally 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.
Harry Potter: Quidditch World Cup
Timing passes, tackles and Snitch chases needs moderate dexterity
South Park Rally
Loose kart handling still rewards clean driving
Harry Potter: Quidditch World Cup leans a little harder on reads, though the gap is small.
Harry Potter: Quidditch World Cup
Versus a friend, faking plays adds light prediction
South Park Rally
Human racers in versus add slight prediction
South Park Rally leans a little harder on variance, though the gap is small.
Harry Potter: Quidditch World Cup
Snitch appearances and combo opportunities add swing
South Park Rally
Random weapon pickups swing race outcomes
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Harry Potter: Quidditch World Cup
Special move charging and team choice reward system knowledge
South Park Rally
Track shortcuts and item timing 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.