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
Tests arena-shooter aim and map-control prediction against human lobbies.

Execution · Grand Arena
Team-based 5v5 Star Wars starfighter combat with cockpit power management.
Halo 2: Anniversary leans Execution (Competitive PvP); Star Wars: Squadrons leans Execution (Grand Arena).
Star Wars: Squadrons leans a little harder on execution, though the gap is small.
Halo 2: Anniversary
Aim, grenades and movement decide every multiplayer duel
Star Wars: Squadrons
Drifting, aim, and throttle tricks decide dogfights
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Halo 2: Anniversary
Predicting human positioning and power-weapon pushes is constant
Star Wars: Squadrons
Human pilots in 5v5 bait, juke, and counter-adapt
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Halo 2: Anniversary
Static spawns and timers leave little true randomness
Star Wars: Squadrons
Full information maps; little randomness
Star Wars: Squadrons leans a little harder on optimization, though the gap is small.
Halo 2: Anniversary
Weapon timers, map control and campaign routes are learnable systems
Star Wars: Squadrons
Power management and loadout meta are solvable layers
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.