head to head
Serious Sam 2 asks more than Grand Theft Auto: San Andreas, and the gap is execution.

Optimization · Practiced Mastery
A sprawling open-world crime epic with RPG-style character stats across a whole state.

Execution · Practiced Mastery
A cartoonish horde shooter sequel of planet-hopping monster massacres.
Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery); Serious Sam 2 leans Execution (Practiced Mastery).
Serious Sam 2 leans clearly harder on execution.
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Serious Sam 2
Sustained horde-clearing aim and strafing
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
Serious Sam 2
Enemy waves are entirely scripted
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto: San Andreas
Territory wars and traffic add light randomness
Serious Sam 2
Cartoon set-pieces surprise once
Grand Theft Auto: San Andreas leans a little harder on optimization, though the gap is small.
Grand Theft Auto: San Andreas
Stats, gym, weapon skill, and routes reward systematic play
Serious Sam 2
Target priority and arena routes are learnable
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.