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

Execution · Practiced Mastery
The sequel adding Horde mode to the campaign-plus-versus cover shooter formula.

Execution · Practiced Mastery
A DS first-person shooter pairing a Metroid campaign with surprisingly competitive online deathmatch.
Gears of War 2 leans Execution (Practiced Mastery); Metroid Prime Hunters leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Gears of War 2
Gnasher battles and movement tech set the ceiling
Metroid Prime Hunters
Stylus aiming on DS is a real physical ceiling
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Gears of War 2
Human opponents in versus drive prediction play
Metroid Prime Hunters
Online deathmatch rewards out-predicting human hunters
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Gears of War 2
Horde spawns add mild randomness
Metroid Prime Hunters
Maps and pickups are fixed
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Gears of War 2
Power-weapon timing and positioning are solvable
Metroid Prime Hunters
Hunter matchups, map control, and pickup timing
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.