head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto V demands more reads; The Swindle demands more variance.

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

Execution · Practiced Mastery
A procedural heist platformer testing careful execution against an upgrade-economy clock.
Grand Theft Auto V leans Execution (Practiced Mastery); The Swindle leans Execution (Practiced Mastery).
The Swindle leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
The Swindle
One-mistake stealth platforming punishes sloppy inputs
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
The Swindle
Guards and drones patrol by script
The Swindle leans clearly harder on variance.
Grand Theft Auto V
Some mission and lobby randomness.
The Swindle
Procedural buildings keep every heist unknown going in
The Swindle leans clearly harder on optimization.
Grand Theft Auto V
Heists, money loops, builds learnable.
The Swindle
Upgrade economy against the doomsday clock is the strategic spine
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.