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

Execution · Practiced Mastery
Planning approaches with recon tools, then executing them under lethal fire.
Gears of War 2 leans Execution (Practiced Mastery); Tom Clancy's Ghost Recon Advanced Warfighter leans Execution (Practiced Mastery).
Gears of War 2 leans a little harder on execution, though the gap is small.
Gears of War 2
Gnasher battles and movement tech set the ceiling
Tom Clancy's Ghost Recon Advanced Warfighter
Lethal firefights punish sloppy aim and exposure
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
Tom Clancy's Ghost Recon Advanced Warfighter
Multiplayer squads outflank and adapt to your habits
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
Tom Clancy's Ghost Recon Advanced Warfighter
Enemy placements are scripted-but-unknown on first attempt
Tom Clancy's Ghost Recon Advanced Warfighter leans a little harder on optimization, though the gap is small.
Gears of War 2
Power-weapon timing and positioning are solvable
Tom Clancy's Ghost Recon Advanced Warfighter
Drone recon, squad orders and approach planning decide missions
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.