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
Free-to-play objective shooter from Splash Damage with mercenary classes.

Execution · Practiced Mastery
A team shooter where aim and positioning against human opponents controls the map.
Dirty Bomb leans Execution (Pure Mechanics); Splatoon 2 leans Execution (Practiced Mastery).
Dirty Bomb leans a little harder on execution, though the gap is small.
Dirty Bomb
Fast strafing gunfights and ability timing need quick hands
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.
Dirty Bomb
Human teams adapt pushes around objective chokepoints
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.
Dirty Bomb
Fixed maps and abilities, minor loadout-card randomness
Splatoon 2
weapon and map rotation randomness
Splatoon 2 leans a little harder on optimization, though the gap is small.
Dirty Bomb
Merc compositions and objective timings reward planning
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.