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 grittier crime story where weighty driving and gunplay carry the experience.

Execution · Practiced Mastery
An early top-down rampage shooter with simple execution demands.
Grand Theft Auto IV leans Execution (Practiced Mastery); Postal leans Execution (Practiced Mastery).
Grand Theft Auto IV leans a little harder on execution, though the gap is small.
Grand Theft Auto IV
Heavier driving and cover shooting reward control.
Postal
top-down shooting and movement
Grand Theft Auto IV leans a little harder on reads, though the gap is small.
Grand Theft Auto IV
Scripted AI, no adaptive opponent modeling.
Postal
enemies use fixed aggressive scripts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto IV
Minor mission variance.
Postal
enemy spawn and pathing randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto IV
Mission routing and weapon picks learnable.
Postal
weapon choice and route clearing
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.