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
Open-world western about an outlaw forced to hunt down his old gang.

Execution · Practiced Mastery
Bleak road-trip shooter where every weapon levels up through use.
Red Dead Redemption leans Execution (Practiced Mastery); Resistance 3 leans Execution (Practiced Mastery).
Resistance 3 leans a little harder on execution, though the gap is small.
Red Dead Redemption
Dead Eye softens but gunplay still wants aim
Resistance 3
Precision shooting with health pickups punishing sloppy play.
Resistance 3 leans a little harder on reads, though the gap is small.
Red Dead Redemption
Multiplayer skirmishes add light human prediction
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.
Red Dead Redemption
Ambient events and spawns vary mildly
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.
Red Dead Redemption
Mission approaches and economy are learnable
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.