head to head
Bulletstorm asks more than Grand Theft Auto V, and the gap is execution.

Execution · Practiced Mastery
An arcade FPS that scores you for killing enemies in the most creative ways possible.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Bulletstorm leans Execution (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Bulletstorm leans clearly harder on execution.
Bulletstorm
Leash, kick, and shot timing drive skillshot chains
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans a little harder on reads, though the gap is small.
Bulletstorm
Enemies are scripted fodder for your combos
Grand Theft Auto V
Online PvP exists but mostly gear/positioning, not modeling.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Bulletstorm
Arenas and spawns are fixed and learnable
Grand Theft Auto V
Some mission and lobby randomness.
Bulletstorm leans clearly harder on optimization.
Bulletstorm
Maximising skillshot score per arena is a solvable puzzle
Grand Theft Auto V
Heists, money loops, builds learnable.
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.