head to head
ZombiU asks more than Red Dead Redemption 2, and the gap is variance.

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

Optimization · Practiced Mastery
A tense survival horror where one bite kills your survivor for good.
Red Dead Redemption 2 leans Execution (Practiced Mastery); ZombiU leans Optimization (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 2
Gunplay and Dead Eye reward aim and timing.
ZombiU
Deliberate cricket-bat timing and panic inventory management
Red Dead Redemption 2 leans a little harder on reads, though the gap is small.
Red Dead Redemption 2
Enemies use scripted AI patterns, not adaptation.
ZombiU
Zombies shamble on fixed logic
ZombiU leans clearly harder on variance.
Red Dead Redemption 2
Some hunting and weather randomness, lightly hidden.
ZombiU
Permadeath runs face unknown spawn placements
ZombiU leans clearly harder on optimization.
Red Dead Redemption 2
Loadouts and routes solvable but loose.
ZombiU
Route knowledge, supply caching, safehouse 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.