head to head
Neither is simply harder - they are hard in different places. Naruto Shippuden: Ultimate Ninja Storm 4 demands more execution; Witch It demands more variance.

Reads · Competitive PvP
Anime arena fighter where managing the substitution gauge is the real duel.

Reads · Pure Mind Games
Hide-and-seek mind games against humans who learn your favourite spots.
Naruto Shippuden: Ultimate Ninja Storm 4 leans Reads (Competitive PvP); Witch It leans Reads (Pure Mind Games).
Naruto Shippuden: Ultimate Ninja Storm 4 leans clearly harder on execution.
Naruto Shippuden: Ultimate Ninja Storm 4
Simple inputs; movement and substitution timing matter
Witch It
Movement and prop placement need modest mechanical skill
Witch It leans a little harder on reads, though the gap is small.
Naruto Shippuden: Ultimate Ninja Storm 4
Versus humans, baiting substitutions is the core game
Witch It
Outguessing human hiders and seekers IS the game
Witch It leans clearly harder on variance.
Naruto Shippuden: Ultimate Ninja Storm 4
Minor support-assist chaos
Witch It
Hiding spots and prop choices are hidden information each round
Naruto Shippuden: Ultimate Ninja Storm 4 leans a little harder on optimization, though the gap is small.
Naruto Shippuden: Ultimate Ninja Storm 4
Team composition and matchup knowledge
Witch It
Map knowledge and spot repertoires help but never solve humans
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.