head to head
Grand Theft Auto V asks more than Stubbs the Zombie in Rebel Without a Pulse, and the gap is reads.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.

Execution · Practiced Mastery
Loose action execution and horde-building through scripted comedy set-pieces.
Grand Theft Auto V leans Execution (Practiced Mastery); Stubbs the Zombie in Rebel Without a Pulse leans Execution (Practiced Mastery).
Grand Theft Auto V leans a little harder on execution, though the gap is small.
Grand Theft Auto V
Driving and shooting demand decent inputs.
Stubbs the Zombie in Rebel Without a Pulse
Limb-throwing and horde wrangling need only loose aim
Grand Theft Auto V leans clearly harder on reads.
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Stubbs the Zombie in Rebel Without a Pulse
Townsfolk and soldiers follow scripted AI
Grand Theft Auto V leans a little harder on variance, though the gap is small.
Grand Theft Auto V
Some mission and lobby randomness.
Stubbs the Zombie in Rebel Without a Pulse
Encounters are fixed set-pieces
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Grand Theft Auto V
Heists, money loops, builds learnable.
Stubbs the Zombie in Rebel Without a Pulse
Conversion economy - building your horde - rewards light 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.