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 · Grand Arena
Fast arena shooter with deep loadout tuning.

Execution · Competitive PvP
Definitive competitive tactical FPS balancing aim mastery with team strategy.
Call of Duty: Modern Warfare III leans Execution (Grand Arena); Counter-Strike: Global Offensive 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: Modern Warfare III
Fast TTK punishes any aim error
Counter-Strike: Global Offensive
Spray control and flick precision at the top
Counter-Strike: Global Offensive leans a little harder on reads, though the gap is small.
Call of Duty: Modern Warfare III
Sliding and pre-aim duels reward prediction
Counter-Strike: Global Offensive
Anti-stratting and mid-round adaptation
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Modern Warfare III
Spawn flips and map traffic add noise
Counter-Strike: Global Offensive
Information hidden until contact
Call of Duty: Modern Warfare III leans a little harder on optimization, though the gap is small.
Call of Duty: Modern Warfare III
Loadouts, perks, attachments heavily tuned
Counter-Strike: Global Offensive
Utility lineups, economy, and default strats
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.