head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Pure Mechanics
A tactical military shooter where aim against human opponents is the deciding factor.

Execution · Pure Mechanics
High-speed aim and movement dominance against human opponents fighting for weapon and map control.
Call of Duty: Modern Warfare leans Execution (Pure Mechanics); Unreal Tournament (1999) leans Execution (Pure Mechanics).
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
aim and reflexes decide engagements
Unreal Tournament (1999)
Shock combo and flak cannon timing demand peak motor precision
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
predicting human opponents' positioning
Unreal Tournament (1999)
Human opponents continuously adapt routes and engagement choices
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
spawns and loadout drops vary
Unreal Tournament (1999)
Map spawns are minor; most information is visible or predictable
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Modern Warfare
loadouts and map knowledge solvable
Unreal Tournament (1999)
Weapon prioritisation and map control are learnable but secondary
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.