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 licensed soccer simulation following the Champions League tournament.
Grand Theft Auto V leans Execution (Practiced Mastery); UEFA Champions League 1999/2000 leans Execution (Practiced Mastery).
UEFA Champions League 1999/2000 leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
UEFA Champions League 1999/2000
passing and shooting require timing precision
UEFA Champions League 1999/2000 leans a little harder on reads, though the gap is small.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
UEFA Champions League 1999/2000
human opponents add some adaptive play
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.
UEFA Champions League 1999/2000
ball physics create minor unpredictability
UEFA Champions League 1999/2000 leans a little harder on optimization, though the gap is small.
Grand Theft Auto V
Heists, money loops, builds learnable.
UEFA Champions League 1999/2000
tactics and formation choices matter
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.