head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is optimization, 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
A cinematic open-world western leaning on shooting feel and atmosphere.
Red Dead Redemption leans Execution (Practiced Mastery); Red Dead Redemption 2 leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Red Dead Redemption
Dead Eye softens but gunplay still wants aim
Red Dead Redemption 2
Gunplay and Dead Eye reward aim and timing.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Red Dead Redemption
Multiplayer skirmishes add light human prediction
Red Dead Redemption 2
Enemies use scripted AI patterns, not adaptation.
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
Red Dead Redemption 2
Some hunting and weather randomness, lightly hidden.
Red Dead Redemption leans a little harder on optimization, though the gap is small.
Red Dead Redemption
Mission approaches and economy are learnable
Red Dead Redemption 2
Loadouts and routes solvable but loose.
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.