head to head
Dead Island asks more than Red Dead Redemption 2, and the gap is optimization.

Optimization · Practiced Mastery
Co-op first-person zombie RPG about improvised weapons on a resort island.

Execution · Practiced Mastery
A cinematic open-world western leaning on shooting feel and atmosphere.
Dead Island leans Optimization (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.
Dead Island
first-person melee timing and stamina
Red Dead Redemption 2
Gunplay and Dead Eye reward aim and timing.
Red Dead Redemption 2 leans a little harder on reads, though the gap is small.
Dead Island
zombies are scripted swarms
Red Dead Redemption 2
Enemies use scripted AI patterns, not adaptation.
Dead Island leans a little harder on variance, though the gap is small.
Dead Island
weapon drops and spawns add noise
Red Dead Redemption 2
Some hunting and weather randomness, lightly hidden.
Dead Island leans clearly harder on optimization.
Dead Island
weapon mods and skill builds carry late game
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.