head to head
Neither is simply harder - they are hard in different places. Call of Duty: Modern Warfare 2 demands more execution; The Isle demands more variance.

Execution · Competitive PvP
Blockbuster 2009 sequel famous for killstreak chains and frantic multiplayer.

Reads · Competitive PvP
Open-world survival sandbox where every dinosaur stalking you is another player.
Call of Duty: Modern Warfare 2 leans Execution (Competitive PvP); The Isle leans Reads (Competitive PvP).
Call of Duty: Modern Warfare 2 leans clearly harder on execution.
Call of Duty: Modern Warfare 2
Fast time-to-kill rewards raw aim and reflex
The Isle
Stamina management and pounce timing in chases
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 2
Outguessing human rotations and flanks
The Isle
Human-controlled dinosaurs ambush and bait
The Isle leans clearly harder on variance.
Call of Duty: Modern Warfare 2
Spawn flips and killstreak randomness
The Isle
Open server world hides who is nearby
Call of Duty: Modern Warfare 2 leans a little harder on optimization, though the gap is small.
Call of Duty: Modern Warfare 2
Killstreak economy, loadout and map knowledge
The Isle
Growth stages, diets, and territory 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.