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

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

Execution · Practiced Mastery
An endless runner testing reaction timing across Spider-Man multiverse stages.
Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery); Marvel Spider-Man Unlimited leans Execution (Practiced Mastery).
Marvel Spider-Man Unlimited leans clearly harder on execution.
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Marvel Spider-Man Unlimited
Reaction timing on swiping and dodging carries runs
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
Marvel Spider-Man Unlimited
Endless runner, no opponent to model
Marvel Spider-Man Unlimited leans a little harder on variance, though the gap is small.
Grand Theft Auto: San Andreas
Territory wars and traffic add light randomness
Marvel Spider-Man Unlimited
Randomized obstacle spawns add some chaos
Grand Theft Auto: San Andreas leans clearly harder on optimization.
Grand Theft Auto: San Andreas
Stats, gym, weapon skill, and routes reward systematic play
Marvel Spider-Man Unlimited
Character collection and upgrades improve scores
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.