head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
The template Far Cry: outposts, predators, and a tropical sandbox.

Execution · Practiced Mastery
A cinematic open-world western leaning on shooting feel and atmosphere.
Far Cry 3 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.
Far Cry 3
Shooting and stealth fundamentals matter.
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.
Far Cry 3
Pirate AI uses fixed alert patterns.
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.
Far Cry 3
Wildlife and outpost spawns randomized.
Red Dead Redemption 2
Some hunting and weather randomness, lightly hidden.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Far Cry 3
Skill trees and weapon mods quickly mastered.
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.