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
Straightforward cover-shooting aim against fully scripted enemy waves.

Execution · Practiced Mastery
Linear postwar crime story driven by cover shootouts and atmosphere.
Army of Two: The Devil's Cartel leans Execution (Practiced Mastery); Mafia II leans Execution (Practiced Mastery).
Army of Two: The Devil's Cartel leans a little harder on execution, though the gap is small.
Army of Two: The Devil's Cartel
Cover shooting rewards decent aim, nothing more
Mafia II
Cover shooting and fistfight timing
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Army of Two: The Devil's Cartel
Cartel enemies follow scripted cover AI
Mafia II
Enemies are scripted
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Army of Two: The Devil's Cartel
Encounters replay identically
Mafia II
Story missions are fixed
Mafia II leans a little harder on optimization, though the gap is small.
Army of Two: The Devil's Cartel
Weapon customization adds light loadout math
Mafia II
Modest; learning encounter layouts
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.