head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

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

Optimization · Practiced Mastery
Kiryu's farewell chapter protecting a baby in seaside Onomichi.
Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery); Yakuza 6: The Song of Life leans Optimization (Practiced Mastery).
Yakuza 6: The Song of Life leans a little harder on execution, though the gap is small.
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Yakuza 6: The Song of Life
Simplified Dragon Engine combat keeps a light timing test.
Yakuza 6: The Song of Life leans a little harder on reads, though the gap is small.
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
Yakuza 6: The Song of Life
Enemies follow fixed scripts.
Grand Theft Auto: San Andreas leans a little harder on variance, though the gap is small.
Grand Theft Auto: San Andreas
Territory wars and traffic add light randomness
Yakuza 6: The Song of Life
Negligible randomness.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto: San Andreas
Stats, gym, weapon skill, and routes reward systematic play
Yakuza 6: The Song of Life
Stat feeding and heat upgrades are straightforward systems.
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.