head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

Execution · Practiced Mastery
Linear postwar crime story driven by cover shootouts and atmosphere.

Execution · Practiced Mastery
An early top-down rampage shooter with simple execution demands.
Mafia II leans Execution (Practiced Mastery); Postal leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Mafia II
Cover shooting and fistfight timing
Postal
top-down shooting and movement
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Mafia II
Enemies are scripted
Postal
enemies use fixed aggressive scripts
Postal leans a little harder on variance, though the gap is small.
Mafia II
Story missions are fixed
Postal
enemy spawn and pathing randomness
Mafia II leans a little harder on optimization, though the gap is small.
Mafia II
Modest; learning encounter layouts
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.