head to head
Neither is simply harder - they are hard in different places. Call of Duty: Warzone demands more variance; StarCraft II: Wings of Liberty demands more reads.

Execution · Grand Arena
Battle royale built on COD's tight gunplay.

Execution · Grand Arena
Real-time strategy where hands, reads, and build optimization all matter at the top.
Call of Duty: Warzone leans Execution (Grand Arena); StarCraft II: Wings of Liberty leans Execution (Grand Arena).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Warzone
Long-range gunfights reward perfect aim
StarCraft II: Wings of Liberty
APM, macro, micro-control under pressure
StarCraft II: Wings of Liberty leans clearly harder on reads.
Call of Duty: Warzone
Rotations and third-party reads decide fights
StarCraft II: Wings of Liberty
1v1 ladder vs adaptive humans modeling you
Call of Duty: Warzone leans clearly harder on variance.
Call of Duty: Warzone
Drops, loot, circles inject real RNG
StarCraft II: Wings of Liberty
map spawns minor; mostly known
StarCraft II: Wings of Liberty leans clearly harder on optimization.
Call of Duty: Warzone
Meta loadouts and rotations heavily solved
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.