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
Ezio rebuilds the Assassin order in Rome, with a cult-classic mind-game multiplayer attached.

Execution · Practiced Mastery
A cinematic Victorian cover shooter about knights hunting half-breeds with exotic weaponry.
Assassin's Creed Brotherhood leans Optimization (Practiced Mastery); The Order: 1886 leans Execution (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 Brotherhood
Kill-streak combat is stylish but easy
The Order: 1886
Standard cover shooting with quick-time events
Assassin's Creed Brotherhood leans a little harder on reads, though the gap is small.
Assassin's Creed Brotherhood
Hide-and-hunt multiplayer ran on human mind-games
The Order: 1886
Scripted setpiece enemies
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Assassin's Creed Brotherhood
Fixed campaign content
The Order: 1886
Heavily authored, nothing random
Assassin's Creed Brotherhood leans a little harder on optimization, though the gap is small.
Assassin's Creed Brotherhood
Recruit management and shop renovation economy
The Order: 1886
Linear encounters, light tactical layer
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.