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
Arcade monster wrestling testing grapple timing and versus-mode throw mindgames.

Execution · Competitive PvP
Arena fighting built on baiting substitutions and timing punishes against humans.
King of the Monsters leans Execution (Competitive PvP); Naruto Shippuden: Ultimate Ninja Storm 3 leans Execution (Competitive PvP).
King of the Monsters leans a little harder on execution, though the gap is small.
King of the Monsters
Grapple timing and positioning decide monster bouts
Naruto Shippuden: Ultimate Ninja Storm 3
Substitution timing and combo confirms need decent hands
Naruto Shippuden: Ultimate Ninja Storm 3 leans a little harder on reads, though the gap is small.
King of the Monsters
Versus humans, throw-tech mindgames add real prediction
Naruto Shippuden: Ultimate Ninja Storm 3
PvP revolves around baiting substitutions from human opponents
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
King of the Monsters
Grapple outcomes carry arcade-era randomness
Naruto Shippuden: Ultimate Ninja Storm 3
Support meter and item randomness barely matter
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
King of the Monsters
Small movesets converge to known optimal loops fast
Naruto Shippuden: Ultimate Ninja Storm 3
Team composition and awakening knowledge add a thin 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.