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 · Pure Mechanics
The sequel that built console online multiplayer around ranked Battle Rifle duels.

Execution · Practiced Mastery
A team shooter where aim and positioning against human opponents controls the map.
Halo 2 leans Execution (Pure Mechanics); Splatoon 2 leans Execution (Practiced Mastery).
Halo 2 leans a little harder on execution, though the gap is small.
Halo 2
BR precision and movement tricks online
Splatoon 2
aim and movement decide ink battles
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Halo 2
Ranked duels hinge on outplaying humans
Splatoon 2
predicting human opponent positioning
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Halo 2
Matchmaking opponents and spawns vary
Splatoon 2
weapon and map rotation randomness
Splatoon 2 leans a little harder on optimization, though the gap is small.
Halo 2
Map control, timers, and weapon spawns
Splatoon 2
loadout and turf strategy 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.