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
Blockbuster 2009 sequel famous for killstreak chains and frantic multiplayer.

Execution · Competitive PvP
Cover-based shotgun duels testing movement execution and positional prediction in multiplayer.
Call of Duty: Modern Warfare 2 leans Execution (Competitive PvP); Gears of War: Ultimate Edition leans Execution (Competitive PvP).
Call of Duty: Modern Warfare 2 leans a little harder on execution, though the gap is small.
Call of Duty: Modern Warfare 2
Fast time-to-kill rewards raw aim and reflex
Gears of War: Ultimate Edition
Wallbounce movement and gnasher duels demand real hands
Call of Duty: Modern Warfare 2 leans a little harder on reads, though the gap is small.
Call of Duty: Modern Warfare 2
Outguessing human rotations and flanks
Gears of War: Ultimate Edition
Multiplayer is constant positional mind-games around cover
Call of Duty: Modern Warfare 2 leans a little harder on variance, though the gap is small.
Call of Duty: Modern Warfare 2
Spawn flips and killstreak randomness
Gears of War: Ultimate Edition
Weapon spawns timed and known; spread mildly random
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
Gears of War: Ultimate Edition
Map control and spawn timing knowledge structure matches
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.