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

Execution · Practiced Mastery
The original 2003 WWII shooter built around cinematic squad set pieces.

Execution · Practiced Mastery
Sandbox crime playground spanning shooting, driving, and a persistent online economy.
Call of Duty leans Execution (Practiced Mastery); Grand Theft Auto V leans Execution (Practiced Mastery).
Call of Duty leans clearly harder on execution.
Call of Duty
Aim and reaction carry the scripted firefights
Grand Theft Auto V
Driving and shooting demand decent inputs.
Call of Duty leans a little harder on reads, though the gap is small.
Call of Duty
Light multiplayer prediction; campaign AI is scripted
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.
Call of Duty
Some spawn and hit unpredictability
Grand Theft Auto V
Some mission and lobby randomness.
Call of Duty leans a little harder on optimization, though the gap is small.
Call of Duty
Memorising set pieces and weapon positions
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.