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

Optimization · Practiced Mastery
A Revolutionary War entry mixing frontier stealth, naval battles, and homestead building.

Optimization · Practiced Mastery
San Francisco hacker sandbox blending stealth, drones, and toy gadgets.
Assassin's Creed III leans Optimization (Practiced Mastery); Watch Dogs 2 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.
Assassin's Creed III
Frontier traversal and counter combat stay forgiving
Watch Dogs 2
Shooting and driving moderate input demands.
Assassin's Creed III leans a little harder on reads, though the gap is small.
Assassin's Creed III
Multiplayer mode involved human deception
Watch Dogs 2
Enemy AI scripted; some PvP invasions exist.
Watch Dogs 2 leans a little harder on variance, though the gap is small.
Assassin's Creed III
Fixed story missions
Watch Dogs 2
Hack outcomes and patrols vary mildly.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Assassin's Creed III
Homestead economy and naval upgrades
Watch Dogs 2
Gadgets, hacks, mission approaches solvable.
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.