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
A twin-stick shooter about aiming and matching weapons to scripted ghost waves.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Ghostbusters: Sanctum of Slime leans Execution (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Ghostbusters: Sanctum of Slime leans a little harder on execution, though the gap is small.
Ghostbusters: Sanctum of Slime
Twin-stick aiming and dodging lead the combat
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans a little harder on reads, though the gap is small.
Ghostbusters: Sanctum of Slime
Ghost enemies follow scripted patterns, not adapting
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Ghostbusters: Sanctum of Slime leans a little harder on variance, though the gap is small.
Ghostbusters: Sanctum of Slime
Enemy spawns and color-matching add some chaos
Grand Theft Auto V
Some mission and lobby randomness.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Ghostbusters: Sanctum of Slime
Matching weapon colors to enemies rewards planning
Grand Theft Auto V
Heists, money loops, builds learnable.
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.