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

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

Execution · Pure Mechanics
Classic football execution - touch, timing and finishing - with human mind-games on top.
Call of Duty 3 leans Execution (Pure Mechanics); ISS Pro Evolution 2 leans Execution (Pure Mechanics).
ISS Pro Evolution 2 leans a little harder on execution, though the gap is small.
Call of Duty 3
Aimbot trivialises both campaign and multiplayer gunfights
ISS Pro Evolution 2
First-touch control, through-ball timing and finishing decide matches
ISS Pro Evolution 2 leans a little harder on reads, though the gap is small.
Call of Duty 3
Multiplayer adds modest human positional prediction
ISS Pro Evolution 2
Versus humans, baiting tackles and disguising passes matters
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
ISS Pro Evolution 2
Slight bounce and keeper randomness within a deterministic sim
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
ISS Pro Evolution 2
Formation and player-role knowledge gives a modest edge
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.