head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

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

Optimization · Practiced Mastery
Aging Ezio chases Altair's legacy through Constantinople in the trilogy's closer.
Assassin's Creed III leans Optimization (Practiced Mastery); Assassin's Creed Revelations 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
Assassin's Creed Revelations
Hookblade traversal and forgiving counters
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Assassin's Creed III
Multiplayer mode involved human deception
Assassin's Creed Revelations
Multiplayer hide-and-hunt kept human bluffing
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Assassin's Creed III
Fixed story missions
Assassin's Creed Revelations
Fixed missions
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
Assassin's Creed Revelations
Den defense and city investment systems
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.