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

Execution · Competitive PvP
Fast aim duels plus predicting human movement on memorised maps.

Execution · Competitive PvP
Hardcore team shooter where one bullet kills and the HUD tells you nothing.
Call of Duty: Modern Warfare Remastered leans Execution (Competitive PvP); Insurgency 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 Remastered
Snap aim and reaction time dominate every gunfight
Insurgency
One-shot lethality rewards precise aim
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 Remastered
Online opponents rotate and adapt; pre-aiming them is prediction
Insurgency
Human squads flank and adapt each round
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 Remastered
Spawns and random lobbies inject per-match noise
Insurgency
No killcam or HUD hides enemy positions
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 Remastered
Map control, loadouts and timing form a learnable meta
Insurgency
Loadout points and objective route knowledge
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.