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

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.

Execution · Practiced Mastery
A one-button Kirby racer whose chaotic City Trial mode became a cult multiplayer favourite.
Grand Theft Auto V leans Execution (Practiced Mastery); Kirby Air Ride leans Execution (Practiced Mastery).
Kirby Air Ride leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Kirby Air Ride
Charge-boost timing and machine handling
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Kirby Air Ride
Local multiplayer rivals add light prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Some mission and lobby randomness.
Kirby Air Ride
City Trial patch and event randomness
Kirby Air Ride leans a little harder on optimization, though the gap is small.
Grand Theft Auto V
Heists, money loops, builds learnable.
Kirby Air Ride
Machine stats and course lines are mappable
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.