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
Hitting fixed pop-rock note charts - execution speed and accuracy, full stop.

Execution · Pure Mechanics
A classic 2D Mario platformer rewarding tight jump execution above all.
Band Hero leans Execution (Pure Mechanics); New Super Mario Bros. U Deluxe 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.
Band Hero
Hitting scrolling note charts on expert is pure hands
New Super Mario Bros. U Deluxe
precise jump and platforming execution
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Band Hero
Charts are fixed - nothing to predict
New Super Mario Bros. U Deluxe
fixed enemy patterns, no adaptation
New Super Mario Bros. U Deluxe leans a little harder on variance, though the gap is small.
Band Hero
Identical note charts every play
New Super Mario Bros. U Deluxe
minor enemy placement randomness
New Super Mario Bros. U Deluxe leans a little harder on optimization, though the gap is small.
Band Hero
Star-power phrasing adds a thin scoring layer
New Super Mario Bros. U Deluxe
level routing for speed/collectibles
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.