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
A crossover anime arena fighter pitting Shonen Jump heroes against each other.

Execution · Competitive PvP
Fast anime fights where combo execution and reading a human rival decide rounds.
Jump Force leans Execution (Competitive PvP); Naruto: Ultimate Ninja 3 leans Execution (Competitive PvP).
Naruto: Ultimate Ninja 3 leans a little harder on execution, though the gap is small.
Jump Force
3D arena combos with generous tracking
Naruto: Ultimate Ninja 3
Combo timing and jutsu clashes reward quick hands
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Jump Force
Human opponents force guard-break guessing
Naruto: Ultimate Ninja 3
Human versus play rewards baiting and habit punishing
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Jump Force
Full information arena duels
Naruto: Ultimate Ninja 3
Fights are deterministic outside clash minigames
Jump Force leans a little harder on optimization, though the gap is small.
Jump Force
Team picks and awakening meter management
Naruto: Ultimate Ninja 3
Character matchups and meter use are a thin learnable layer
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.