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 · Competitive PvP
Hardcore team shooter where one bullet kills and the HUD tells you nothing.

Execution · Pure Mechanics
High-speed aim and movement dominance against human opponents fighting for weapon and map control.
Insurgency leans Execution (Competitive PvP); Unreal Tournament (1999) leans Execution (Pure Mechanics).
Unreal Tournament (1999) leans a little harder on execution, though the gap is small.
Insurgency
One-shot lethality rewards precise aim
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.
Insurgency
Human squads flank and adapt each round
Unreal Tournament (1999)
Human opponents continuously adapt routes and engagement choices
Insurgency leans a little harder on variance, though the gap is small.
Insurgency
No killcam or HUD hides enemy positions
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.
Insurgency
Loadout points and objective route knowledge
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.