head to head
Warhammer 40,000: Space Marine 2 asks more than Red Dead Redemption 2, and the gap is execution.

Execution · Practiced Mastery
A cinematic open-world western leaning on shooting feel and atmosphere.

Execution · Practiced Mastery
Co-op-focused action sequel hurling Titus against Tyranid swarms with parry-heavy melee combat.
Red Dead Redemption 2 leans Execution (Practiced Mastery); Warhammer 40,000: Space Marine 2 leans Execution (Practiced Mastery).
Warhammer 40,000: Space Marine 2 leans clearly harder on execution.
Red Dead Redemption 2
Gunplay and Dead Eye reward aim and timing.
Warhammer 40,000: Space Marine 2
Parry, dodge and gun-strike timing against swarms
Warhammer 40,000: Space Marine 2 leans a little harder on reads, though the gap is small.
Red Dead Redemption 2
Enemies use scripted AI patterns, not adaptation.
Warhammer 40,000: Space Marine 2
PvP Eternal War adds some human prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Red Dead Redemption 2
Some hunting and weather randomness, lightly hidden.
Warhammer 40,000: Space Marine 2
Tyranid swarm spawns vary run to run
Warhammer 40,000: Space Marine 2 leans a little harder on optimization, though the gap is small.
Red Dead Redemption 2
Loadouts and routes solvable but loose.
Warhammer 40,000: Space Marine 2
Class builds and perk loadouts reward planning
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.