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

Execution · Practiced Mastery
Open-world driving that tests car control with a tuning layer underneath.

Optimization · Practiced Mastery
A sprawling open-world crime epic with RPG-style character stats across a whole state.
Forza Horizon leans Execution (Practiced Mastery); Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery).
Forza Horizon leans clearly harder on execution.
Forza Horizon
Driving skill with assists off carries every event
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Forza Horizon leans a little harder on reads, though the gap is small.
Forza Horizon
AI drivatars follow patterns; casual online adds little
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 Horizon
The open world is fixed and fully discoverable
Grand Theft Auto: San Andreas
Territory wars and traffic add light randomness
Grand Theft Auto: San Andreas leans a little harder on optimization, though the gap is small.
Forza Horizon
Car tuning and racing lines reward systematic study
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.