head to head
ModNation Racers: Road Trip asks more than Grand Theft Auto: San Andreas, and the gap is reads.

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

Execution · Practiced Mastery
A kart racer testing driving precision and item management on user-created tracks.
Grand Theft Auto: San Andreas leans Optimization (Practiced Mastery); ModNation Racers: Road Trip leans Execution (Practiced Mastery).
ModNation Racers: Road Trip leans clearly harder on execution.
Grand Theft Auto: San Andreas
Flying school and drive-bys need decent hands
ModNation Racers: Road Trip
Drifting and boosting at speed demands driving precision
ModNation Racers: Road Trip leans clearly harder on reads.
Grand Theft Auto: San Andreas
Gang AI is scripted, never adaptive
ModNation Racers: Road Trip
Versus humans, anticipating weapon use matters somewhat
ModNation Racers: Road Trip leans clearly harder on variance.
Grand Theft Auto: San Andreas
Territory wars and traffic add light randomness
ModNation Racers: Road Trip
Item pickups and weapon spread add kart-racer chaos
Grand Theft Auto: San Andreas leans a little harder on optimization, though the gap is small.
Grand Theft Auto: San Andreas
Stats, gym, weapon skill, and routes reward systematic play
ModNation Racers: Road Trip
Track lines, boost management and shortcuts 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.