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

Execution · Practiced Mastery
Accessible car control amid demolition chaos rather than precision racing.

Optimization · Practiced Mastery
A sprawling open-world crime epic with RPG-style character stats across a whole state.
Dirt Showdown leans Execution (Practiced Mastery); Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery).
Dirt Showdown leans clearly harder on execution.
Dirt Showdown
Drifting, boosting and ramming need solid car control
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
Dirt Showdown leans clearly harder on reads.
Dirt Showdown
Demolition modes reward predicting human movement a little
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Dirt Showdown
Crash physics and pack chaos add randomness
Grand Theft Auto: San Andreas
Territory wars and traffic add light randomness
Grand Theft Auto: San Andreas leans clearly harder on optimization.
Dirt Showdown
Event types and boost routes are quickly learnable
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.