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
Licensed bike riding and building that asks little beyond basic handling.

Execution · Practiced Mastery
Linear postwar crime story driven by cover shootouts and atmosphere.
American Chopper leans Execution (Practiced Mastery); Mafia II leans Execution (Practiced Mastery).
American Chopper leans a little harder on execution, though the gap is small.
American Chopper
Bike handling on missions is the only real demand
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.
American Chopper
AI riders follow fixed lines
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.
American Chopper
Courses and missions are scripted
Mafia II
Story missions are fixed
Mafia II leans a little harder on optimization, though the gap is small.
American Chopper
Chopper part choices matter, but shallowly
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.