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

Execution · Practiced Mastery
A maze-chase arcade game testing dodging under a scrolling screen's pressure.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Devil World leans Execution (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Devil World leans clearly harder on execution.
Devil World
Dodging demons while the scrolling maze crushes you is twitch
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans clearly harder on reads.
Devil World
Demons chase on simple fixed logic
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.
Devil World
Scroll direction shifts add mild unpredictability
Grand Theft Auto V
Some mission and lobby randomness.
Devil World leans a little harder on optimization, though the gap is small.
Devil World
Maze routes and cross timing are learnable patterns
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.