head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is reads, and it is a single point.

Execution · Competitive PvP
Substitution baiting against humans atop simple anime-fighter inputs and team picks.

Execution · Practiced Mastery
Tests arcade grapple timing with shallow systems underneath.
Naruto Shippuden: Ultimate Ninja Storm 2 leans Execution (Competitive PvP); WCW Nitro leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Naruto Shippuden: Ultimate Ninja Storm 2
Timing substitutions and combos matters but inputs are simple
WCW Nitro
Fast grapple timing in an arcade-paced wrestling frame
Naruto Shippuden: Ultimate Ninja Storm 2 leans a little harder on reads, though the gap is small.
Naruto Shippuden: Ultimate Ninja Storm 2
Versus humans, baiting substitutions is the real layer
WCW Nitro
Human versus play rewards mild move prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Naruto Shippuden: Ultimate Ninja Storm 2
Nothing hidden once both characters are known
WCW Nitro
Little randomness beyond AI behaviour
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Naruto Shippuden: Ultimate Ninja Storm 2
Team composition and chakra management have solvable lines
WCW Nitro
Learning each wrestler's move list is quickly exhausted
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.