head to head
Neither is simply harder - they are hard in different places. BloodRayne 2 demands more execution; Grand Theft Auto: San Andreas demands more optimization.

Execution · Practiced Mastery
An action-hack-and-slash game centered on combo execution against scripted foes.

Optimization · Practiced Mastery
A sprawling open-world crime epic with RPG-style character stats across a whole state.
BloodRayne 2 leans Execution (Practiced Mastery); Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery).
BloodRayne 2 leans clearly harder on execution.
BloodRayne 2
combo-based melee and dodge timing
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
BloodRayne 2
enemies run fixed attack scripts
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
Grand Theft Auto: San Andreas leans a little harder on variance, though the gap is small.
BloodRayne 2
minor damage/drop randomness
Grand Theft Auto: San Andreas
Territory wars and traffic add light randomness
Grand Theft Auto: San Andreas leans clearly harder on optimization.
BloodRayne 2
upgrade path and combo optimization
Grand Theft Auto: San Andreas
Stats, gym, weapon skill, and routes reward systematic play
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.