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
A basketball sim testing shot timing and tactical play against opponents.

Execution · Practiced Mastery
A team shooter where aim and positioning against human opponents controls the map.
NBA 2K3 leans Execution (Practiced Mastery); Splatoon 2 leans Execution (Practiced Mastery).
Splatoon 2 leans a little harder on execution, though the gap is small.
NBA 2K3
Shooting and dribble timing decide plays
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.
NBA 2K3
Human opponents reward reading offense and defense
Splatoon 2
predicting human opponent positioning
NBA 2K3 leans a little harder on variance, though the gap is small.
NBA 2K3
Shot success carries randomness
Splatoon 2
weapon and map rotation randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
NBA 2K3
Playcalling, rotations, and team management 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.