head to head
Neither is simply harder - they are hard in different places. Dragon's Dogma 2 demands more optimization; Grand Theft Auto V demands more reads.

Optimization · Practiced Mastery
The systems-heavy sequel where the journey itself is the danger.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Dragon's Dogma 2 leans Optimization (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Dragon's Dogma 2
Physical combat and monster climbing demand handling
Grand Theft Auto V
Driving and shooting demand decent inputs.
Grand Theft Auto V leans clearly harder on reads.
Dragon's Dogma 2
Scripted monster ecology, no adaptation
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.
Dragon's Dogma 2
Emergent travel encounters surprise until learned
Grand Theft Auto V
Some mission and lobby randomness.
Dragon's Dogma 2 leans clearly harder on optimization.
Dragon's Dogma 2
Vocation builds and pawn logistics reward mastery
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.