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

Execution · Grand Arena
Open military simulator and PvP sandbox.

Execution · Grand Arena
Battle royale built on COD's tight gunplay.
Arma 3 leans Execution (Grand Arena); Call of Duty: Warzone leans Execution (Grand Arena).
Call of Duty: Warzone leans a little harder on execution, though the gap is small.
Arma 3
Bullet drop, stance, sway, weight all matter
Call of Duty: Warzone
Long-range gunfights reward perfect aim
Arma 3 leans a little harder on reads, though the gap is small.
Arma 3
PvP and milsim ops reward prediction
Call of Duty: Warzone
Rotations and third-party reads decide fights
Call of Duty: Warzone leans a little harder on variance, though the gap is small.
Arma 3
Mission scripts and AI behavior vary
Call of Duty: Warzone
Drops, loot, circles inject real RNG
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Arma 3
Loadout planning and tactics solvable
Call of Duty: Warzone
Meta loadouts and rotations heavily solved
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.