head to head
Far Cry 4 asks more than Army of Two, and the gap is optimization.

Execution · Practiced Mastery
A co-op third-person shooter built around two mercenaries juggling enemy aggro together.

Execution · Practiced Mastery
A Himalayan open-world shooter refining the outpost-clearing formula.
Army of Two leans Execution (Practiced Mastery); Far Cry 4 leans Execution (Practiced Mastery).
Far Cry 4 leans a little harder on execution, though the gap is small.
Army of Two
Cover shooting and co-op timing
Far Cry 4
Gunplay plus gyrocopter and elephant chaos
Army of Two leans a little harder on reads, though the gap is small.
Army of Two
Aggro system is mappable, not adaptive
Far Cry 4
Scripted outpost AI
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Army of Two
Scripted setpieces
Far Cry 4
Wildlife and patrol variation
Far Cry 4 leans clearly harder on optimization.
Army of Two
Weapon upgrades and aggro manipulation
Far Cry 4
Outpost approaches and skill trees are plannable
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.