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 · Pure Mechanics
Physics-balance execution refined over thousands of attempts on fixed tracks.
Cuphead leans Execution (Pure Mechanics); Trials HD leans Execution (Pure Mechanics).
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.
Trials HD
Throttle balance and weight shifts demand frame-tight physical control
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.
Trials HD
Solo against static obstacle courses
Cuphead leans a little harder on variance, though the gap is small.
Cuphead
Minor attack-order shuffling between phases.
Trials HD
Tracks are identical every single attempt
Cuphead leans a little harder on optimization, though the gap is small.
Cuphead
Loadouts and boss phase order are fully learnable.
Trials HD
Finding the optimal line through each obstacle rewards study
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.