head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto V demands more reads; Max Payne 2: The Fall of Max Payne demands more execution.

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

Execution · Practiced Mastery
Tighter, sadder sequel that perfects the slow-motion noir gunfight.
Grand Theft Auto V leans Execution (Practiced Mastery); Max Payne 2: The Fall of Max Payne leans Execution (Practiced Mastery).
Max Payne 2: The Fall of Max Payne leans clearly harder on execution.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Max Payne 2: The Fall of Max Payne
refined bullet-time gunplay and physics kills
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Max Payne 2: The Fall of Max Payne
fully scripted opposition
Grand Theft Auto V leans a little harder on variance, though the gap is small.
Grand Theft Auto V
Some mission and lobby randomness.
Max Payne 2: The Fall of Max Payne
deterministic encounters
Max Payne 2: The Fall of Max Payne leans a little harder on optimization, though the gap is small.
Grand Theft Auto V
Heists, money loops, builds learnable.
Max Payne 2: The Fall of Max Payne
bullet-time meter management and routing
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.