head to head
Neither is simply harder - they are hard in different places. Grand Theft Auto: San Andreas demands more optimization; Xybots demands more execution.

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

Execution · Practiced Mastery
Maze-clearing shooter execution with light energy and upgrade management.
Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery); Xybots leans Execution (Practiced Mastery).
Xybots leans clearly harder on execution.
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Xybots
First-person maze gunfights need quick turning and aim
Xybots leans a little harder on reads, though the gap is small.
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
Xybots
Robot enemies follow simple fixed behaviours
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
Xybots
Maze layouts are unknown until explored, then static
Grand Theft Auto: San Andreas leans clearly harder on optimization.
Grand Theft Auto: San Andreas
Stats, gym, weapon skill, and routes reward systematic play
Xybots
Energy management and upgrade purchases 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.