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 · Practiced Mastery
Memorising scripted bullet waves and executing clean dodges for score.

Execution · Pure Mechanics
A run-and-gun boss rush about dodging scripted patterns with tight inputs.
Aero Fighters 3 leans Execution (Practiced Mastery); Cuphead leans Execution (Pure Mechanics).
Cuphead leans a little harder on execution, though the gap is small.
Aero Fighters 3
Dodging dense bullet patterns is the whole challenge
Cuphead
Tight dodging and parry timing decide every boss.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Aero Fighters 3
Enemy waves are fully scripted, nothing adapts
Cuphead
Bosses cycle scripted phases; no adaptation to player.
Aero Fighters 3 leans a little harder on variance, though the gap is small.
Aero Fighters 3
Minor item drops aside, patterns are fixed once learned
Cuphead
Minor attack-order shuffling between phases.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Aero Fighters 3
Memorising spawns, routes and ship choice drives high scores
Cuphead
Loadouts and boss phase order are fully learnable.
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.