head to head
Neither is simply harder - they are hard in different places. Arma 3 demands more variance; StarCraft II: Wings of Liberty demands more optimization.

Execution · Grand Arena
Open military simulator and PvP sandbox.

Execution · Grand Arena
Real-time strategy where hands, reads, and build optimization all matter at the top.
Arma 3 leans Execution (Grand Arena); StarCraft II: Wings of Liberty leans Execution (Grand Arena).
StarCraft II: Wings of Liberty leans a little harder on execution, though the gap is small.
Arma 3
Bullet drop, stance, sway, weight all matter
StarCraft II: Wings of Liberty
APM, macro, micro-control under pressure
StarCraft II: Wings of Liberty leans a little harder on reads, though the gap is small.
Arma 3
PvP and milsim ops reward prediction
StarCraft II: Wings of Liberty
1v1 ladder vs adaptive humans modeling you
Arma 3 leans clearly harder on variance.
Arma 3
Mission scripts and AI behavior vary
StarCraft II: Wings of Liberty
map spawns minor; mostly known
StarCraft II: Wings of Liberty leans clearly harder on optimization.
Arma 3
Loadout planning and tactics solvable
StarCraft II: Wings of Liberty
build orders, economy curves 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.