head to head
Neither is simply harder - they are hard in different places. Deadbolt demands more execution; Grand Theft Auto V demands more reads.

Execution · Practiced Mastery
Planning a clean route through each level, then executing it without a single mistake.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Deadbolt leans Execution (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Deadbolt leans clearly harder on execution.
Deadbolt
One-hit deaths demand precise shots and clean movement
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans clearly harder on reads.
Deadbolt
Undead follow patrol scripts, never modelling the player
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.
Deadbolt
Enemy placements are mostly fixed with minor behavioural noise
Grand Theft Auto V
Some mission and lobby randomness.
Deadbolt leans clearly harder on optimization.
Deadbolt
Planning entry routes and kill order is half the level
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.