head to head
Metal Gear Solid 3: Subsistence asks more than Grand Theft Auto V, and the gap is optimization.

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

Optimization · Practiced Mastery
Stealth systems mastery against scripted guards with moderate execution needs.
Grand Theft Auto V leans Execution (Practiced Mastery); Metal Gear Solid 3: Subsistence leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Metal Gear Solid 3: Subsistence
CQC, aiming and timed escapes demand real but moderate precision
Grand Theft Auto V leans a little harder on reads, though the gap is small.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Metal Gear Solid 3: Subsistence
Guards and bosses run rich but ultimately scripted behaviours
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.
Metal Gear Solid 3: Subsistence
Patrols and boss quirks are unknown only until studied
Metal Gear Solid 3: Subsistence leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
Metal Gear Solid 3: Subsistence
Camo, food and route systems reward deep mastery
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.