head to head
Resident Evil 6 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
Sprawling action horror with four campaigns and a surprisingly deep combat system.
Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery); Resident Evil 6 leans Execution (Practiced Mastery).
Resident Evil 6 leans clearly harder on execution.
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Resident Evil 6
Deep melee-and-gunplay movement system rewards mechanics
Resident Evil 6 leans a little harder on reads, though the gap is small.
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
Resident Evil 6
Agent Hunt PvP adds a sliver of prediction
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
Resident Evil 6
Set-piece campaigns are fixed after first sight
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
Resident Evil 6
Skill builds and Mercenaries combos 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.