head to head
Assassin's Creed IV: Black Flag asks more than Assassin's Creed II, and the gap is reads.

Optimization · Practiced Mastery
Ezio's Renaissance revenge tale of parkour, assassination, and villa-building across Italy.

Optimization · Practiced Mastery
An open-world pirate adventure where upgrading the Jackdaw matters more than the blade.
Assassin's Creed II leans Optimization (Practiced Mastery); Assassin's Creed IV: Black Flag 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 II
Counter-heavy combat stays forgiving
Assassin's Creed IV: Black Flag
Naval broadsides and boarding need modest timing
Assassin's Creed IV: Black Flag leans clearly harder on reads.
Assassin's Creed II
Guards follow scripts
Assassin's Creed IV: Black Flag
Multiplayer deception mode; campaign is scripted
Assassin's Creed IV: Black Flag leans a little harder on variance, though the gap is small.
Assassin's Creed II
Fixed world and missions
Assassin's Creed IV: Black Flag
Weather, convoys, and hunting spawns
Assassin's Creed IV: Black Flag leans a little harder on optimization, though the gap is small.
Assassin's Creed II
Villa economy and route planning, lightly
Assassin's Creed IV: Black Flag
Ship upgrades and fleet economy drive progress
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.