head to head
Warhammer 40,000: Space Marine 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
Co-op-focused action sequel hurling Titus against Tyranid swarms with parry-heavy melee combat.
Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery); Warhammer 40,000: Space Marine 2 leans Execution (Practiced Mastery).
Warhammer 40,000: Space Marine 2 leans clearly harder on execution.
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Warhammer 40,000: Space Marine 2
Parry, dodge and gun-strike timing against swarms
Warhammer 40,000: Space Marine 2 leans clearly harder on reads.
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
Warhammer 40,000: Space Marine 2
PvP Eternal War adds some human 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
Warhammer 40,000: Space Marine 2
Tyranid swarm spawns vary run to run
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
Warhammer 40,000: Space Marine 2
Class builds and perk loadouts reward planning
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.