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

Execution · Pure Mechanics
A run-and-gun boss rush about dodging scripted patterns with tight inputs.

Execution · Practiced Mastery
A Cave bullet hell demanding the highest execution ceiling of any mainstream shmup, with a rank system that punishes passivity.
Cuphead leans Execution (Pure Mechanics); Mushihimesama 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.
Cuphead
Tight dodging and parry timing decide every boss.
Mushihimesama
Ultra Maniac difficulty requires inhuman movement precision
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Cuphead
Bosses cycle scripted phases; no adaptation to player.
Mushihimesama
All bullet patterns are scripted Cave bullet-hell formations
Mushihimesama leans a little harder on variance, though the gap is small.
Cuphead
Minor attack-order shuffling between phases.
Mushihimesama
Rank system alters bullet speed based on play style
Mushihimesama leans a little harder on optimization, though the gap is small.
Cuphead
Loadouts and boss phase order are fully learnable.
Mushihimesama
Shot type selection, rank management, and scoring routes are solvable
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.