head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Execution · Pure Mechanics
WWII gunfight execution with light multiplayer prediction.

Execution · Competitive PvP
Arcade monster wrestling testing grapple timing and versus-mode throw mindgames.
Call of Duty 3 leans Execution (Pure Mechanics); King of the Monsters leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty 3
Aimbot trivialises both campaign and multiplayer gunfights
King of the Monsters
Grapple timing and positioning decide monster bouts
King of the Monsters leans a little harder on reads, though the gap is small.
Call of Duty 3
Multiplayer adds modest human positional prediction
King of the Monsters
Versus humans, throw-tech mindgames add real prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty 3
Scripted setpieces and spawn flow add minor unknowns
King of the Monsters
Grapple outcomes carry arcade-era randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty 3
Map knowledge and weapon choice reward light study
King of the Monsters
Small movesets converge to known optimal loops fast
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.