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
Fast arena shooter with deep loadout tuning.

Execution · Competitive PvP
Gunplay and predicting human squads across large-scale and extraction modes.
Call of Duty: Modern Warfare III leans Execution (Grand Arena); Delta Force leans Execution (Competitive PvP).
Call of Duty: Modern Warfare III leans a little harder on execution, though the gap is small.
Call of Duty: Modern Warfare III
Fast TTK punishes any aim error
Delta Force
Gunfights and recoil control decide most engagements
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Modern Warfare III
Sliding and pre-aim duels reward prediction
Delta Force
Predicting human rotations and pushes runs through every mode
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
Delta Force
Extraction loot and operator gadget chaos add noise
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
Delta Force
Loadout economy and objective sequencing set the floor
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.