head to head
Forza Motorsport 4 asks more than Grand Theft Auto: San Andreas, and the gap is execution.

Execution · Practiced Mastery
A sim racer where driving precision and car tuning both determine lap times.

Optimization · Practiced Mastery
A sprawling open-world crime epic with RPG-style character stats across a whole state.
Forza Motorsport 4 leans Execution (Practiced Mastery); Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery).
Forza Motorsport 4 leans clearly harder on execution.
Forza Motorsport 4
precise braking, throttle, and racing lines
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Forza Motorsport 4 leans a little harder on reads, though the gap is small.
Forza Motorsport 4
AI drivers don't meaningfully adapt
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
Grand Theft Auto: San Andreas leans a little harder on variance, though the gap is small.
Forza Motorsport 4
minor race incident randomness
Grand Theft Auto: San Andreas
Territory wars and traffic add light randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Forza Motorsport 4
car tuning and upgrade optimization
Grand Theft Auto: San Andreas
Stats, gym, weapon skill, and routes reward systematic play
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.