head to head
Splatoon asks more than Worms Rumble, and the gap is optimization.

Execution · Competitive PvP
Territory control through shooter execution and constant prediction of adapting human teams.

Execution · Competitive PvP
Real-time arena aim duels against human worms with randomised weapon pickups.
Splatoon leans Execution (Competitive PvP); Worms Rumble leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Splatoon
Aim, swim-form movement and ink management are constant demands
Worms Rumble
Real-time aim and movement decide brawls, unlike turn-based Worms
Splatoon leans a little harder on reads, though the gap is small.
Splatoon
Human opponents adapt flanks and pushes every match
Worms Rumble
Human opponents in arena and royale modes can be predicted
Worms Rumble leans a little harder on variance, though the gap is small.
Splatoon
Hidden squids in ink create momentary information gaps
Worms Rumble
Weapon crate spawns and drop positions add randomness
Splatoon leans clearly harder on optimization.
Splatoon
Weapon kits, map control timing and gear builds reward study
Worms Rumble
Loadout knowledge and map control matter but stay shallow
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.