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 · Pure Mechanics
Routine shooter aim through scripted cartel firefights.
Call of Duty 3 leans Execution (Pure Mechanics); Call of Juarez: The Cartel leans Execution (Pure Mechanics).
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
Call of Juarez: The Cartel
Standard FPS gunfights run on aim alone
Call of Duty 3 leans a little harder on reads, though the gap is small.
Call of Duty 3
Multiplayer adds modest human positional prediction
Call of Juarez: The Cartel
Co-op secret objectives add mild teammate suspicion
Call of Duty 3 leans a little harder on variance, though the gap is small.
Call of Duty 3
Scripted setpieces and spawn flow add minor unknowns
Call of Juarez: The Cartel
Enemy waves spawn identically each run
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
Call of Juarez: The Cartel
Weapon levelling is a thin progression layer
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.