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.

Reads · Competitive PvP
A 3D arena fighter where extendable-arm punches curve mid-flight in PvP duels.

Reads · Competitive PvP
Anime arena fighter where managing the substitution gauge is the real duel.
ARMS leans Reads (Competitive PvP); Naruto Shippuden: Ultimate Ninja Storm 4 leans Reads (Competitive PvP).
ARMS leans a little harder on execution, though the gap is small.
ARMS
Curving punches and dodge timing
Naruto Shippuden: Ultimate Ninja Storm 4
Simple inputs; movement and substitution timing matter
ARMS leans a little harder on reads, though the gap is small.
ARMS
Whiff-punish games against adapting humans
Naruto Shippuden: Ultimate Ninja Storm 4
Versus humans, baiting substitutions is the core game
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
ARMS
Minor stage and item randomness
Naruto Shippuden: Ultimate Ninja Storm 4
Minor support-assist chaos
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
ARMS
Arm loadout counters and matchup study
Naruto Shippuden: Ultimate Ninja Storm 4
Team composition and matchup knowledge
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.