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.

Execution · Pure Mechanics
Treyarch's future-tech Call of Duty that anchored competitive console FPS.

Execution · Competitive PvP
A tactical shooter where precise gunplay against human opposition is the deciding skill.
Call of Duty: Black Ops II leans Execution (Pure Mechanics); Counter-Strike: Condition Zero leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Black Ops II
Snap aim and movement speed decide split-second gunfights
Counter-Strike: Condition Zero
aim and spray control decide duels
Counter-Strike: Condition Zero leans a little harder on reads, though the gap is small.
Call of Duty: Black Ops II
Human lobbies adapt rotations; pros mind-game spawns
Counter-Strike: Condition Zero
predicting human opponent positioning
Call of Duty: Black Ops II leans a little harder on variance, though the gap is small.
Call of Duty: Black Ops II
Spawn flips and scorestreak chaos inject randomness
Counter-Strike: Condition Zero
buy-round economy and drops vary slightly
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Black Ops II
Pick-10 classes and streak economies reward optimization
Counter-Strike: Condition Zero
economy management and utility usage solvable
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.