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
A modern Gears entry spanning campaign, Horde, Escape, and ranked versus.

Execution · Practiced Mastery
The sequel adding Horde mode to the campaign-plus-versus cover shooter formula.
Gears 5 leans Execution (Practiced Mastery); Gears of War 2 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 5
Movement tech and shotgun duels remain the core test
Gears of War 2
Gnasher battles and movement tech set the ceiling
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Gears 5
Ranked versus rewards out-thinking human opponents
Gears of War 2
Human opponents in versus drive prediction play
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Gears 5
Escape and Horde inject some run variance
Gears of War 2
Horde spawns add mild randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Gears 5
Character ultimates and map control are learnable
Gears of War 2
Power-weapon timing and positioning are solvable
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.