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
Street racer with stylized arcade handling.
Grand Theft Auto V leans Execution (Practiced Mastery); Need for Speed Unbound leans Execution (Practiced Mastery).
Need for Speed Unbound leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Need for Speed Unbound
Arcade drift and grip 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.
Need for Speed Unbound
Online lobbies, AI cops
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.
Need for Speed Unbound
Heat level and cop chase RNG
Need for Speed Unbound leans a little harder on optimization, though the gap is small.
Grand Theft Auto V
Heists, money loops, builds learnable.
Need for Speed Unbound
Car build, betting strategy, garage growth
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.