head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto V demands more reads; Sniper Ghost Warrior Contracts 2 demands more optimization.

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

Execution · Practiced Mastery
Planning a kill order and landing extreme-range ballistic shots against scripted patrols.
Grand Theft Auto V leans Execution (Practiced Mastery); Sniper Ghost Warrior Contracts 2 leans Execution (Practiced Mastery).
Sniper Ghost Warrior Contracts 2 leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Sniper Ghost Warrior Contracts 2
Aimbot trivialises the long-range ballistic shots that define it
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Sniper Ghost Warrior Contracts 2
Enemy patrols follow fixed scripts, never adapting to your tactics
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.
Sniper Ghost Warrior Contracts 2
Wind and patrol layouts are unknown until scouted, then fixed
Sniper Ghost Warrior Contracts 2 leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Sniper Ghost Warrior Contracts 2
Planning routes, shot order and contract objectives is half the game
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.