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
Stick execution and opponent prediction inside licensed tournament football.
Gears of War 2 leans Execution (Practiced Mastery); UEFA Champions League 2006–2007 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
UEFA Champions League 2006–2007
Pass timing and shot placement decide most goals
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
UEFA Champions League 2006–2007
Human opponents bait tackles and disguise attacks
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
UEFA Champions League 2006–2007
Deflections and AI bounces add match noise
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
UEFA Champions League 2006–2007
Squad selection and tactical setup are solvable preparation
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.