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

Execution · Practiced Mastery
Bleak road-trip shooter where every weapon levels up through use.
Call of Duty leans Execution (Practiced Mastery); Resistance 3 leans Execution (Practiced Mastery).
Call of Duty leans a little harder on execution, though the gap is small.
Call of Duty
Aim and reaction carry the scripted firefights
Resistance 3
Precision shooting with health pickups punishing sloppy play.
Call of Duty leans a little harder on reads, though the gap is small.
Call of Duty
Light multiplayer prediction; campaign AI is scripted
Resistance 3
Mostly scripted campaign; smaller multiplayer scene.
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
Resistance 3
First-run encounter unknowns.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty
Memorising set pieces and weapon positions
Resistance 3
Weapon-leveling wheel rewards deliberate arsenal investment.
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.