head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

Optimization · Practiced Mastery
Twin assassins seize Victorian London borough by borough with gang warfare and a rope launcher.

Execution · Practiced Mastery
A cinematic open-world western leaning on shooting feel and atmosphere.
Assassin's Creed Syndicate leans Optimization (Practiced Mastery); Red Dead Redemption 2 leans Execution (Practiced Mastery).
Red Dead Redemption 2 leans a little harder on execution, though the gap is small.
Assassin's Creed Syndicate
Rope-launcher traversal and simple brawling
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.
Assassin's Creed Syndicate
Gangs are scripted
Red Dead Redemption 2
Enemies use scripted AI patterns, not adaptation.
Red Dead Redemption 2 leans a little harder on variance, though the gap is small.
Assassin's Creed Syndicate
Fixed activities
Red Dead Redemption 2
Some hunting and weather randomness, lightly hidden.
Assassin's Creed Syndicate leans a little harder on optimization, though the gap is small.
Assassin's Creed Syndicate
Gang upgrades and borough takeover planning
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.