head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Pure Mechanics
A classic 2D Mario platformer rewarding tight jump execution above all.

Execution · Pure Mechanics
Pure call-and-response rhythm timing with a freestyle layer for top ranks.
New Super Mario Bros. U Deluxe leans Execution (Pure Mechanics); PaRappa the Rapper 2 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.
New Super Mario Bros. U Deluxe
precise jump and platforming execution
PaRappa the Rapper 2
Hitting button cues on beat is the entire game
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
New Super Mario Bros. U Deluxe
fixed enemy patterns, no adaptation
PaRappa the Rapper 2
Teachers rap fixed lines, nothing adapts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
New Super Mario Bros. U Deluxe
minor enemy placement randomness
PaRappa the Rapper 2
Songs are fully deterministic call-and-response
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
New Super Mario Bros. U Deluxe
level routing for speed/collectibles
PaRappa the Rapper 2
Freestyle scoring for Cool rank rewards learned improvisation patterns
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.