head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

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

Execution · Practiced Mastery
Light web-swinging execution over a scripted open-world checklist.
Mafia II leans Execution (Practiced Mastery); Spider-Man 3 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
Spider-Man 3
Swing control and combo timing carry the combat
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
Spider-Man 3
Enemies follow fixed scripts, nothing models you
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Mafia II
Story missions are fixed
Spider-Man 3
Open-world missions are static once discovered
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Mafia II
Modest; learning encounter layouts
Spider-Man 3
Upgrade paths and mission objectives are shallowly solvable
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.