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 · Pure Mechanics
Pioneering rhythm game where a rapping dog believes his way through button-cue raps.

Execution · Pure Mechanics
Minimalist rhythm minigame collection demanding near-perfect beat timing.
PaRappa the Rapper leans Execution (Pure Mechanics); Rhythm Heaven leans Execution (Pure Mechanics).
Rhythm Heaven leans a little harder on execution, though the gap is small.
PaRappa the Rapper
Hitting button cues on beat is the whole game
Rhythm Heaven
Pure timing precision against audio cues.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
PaRappa the Rapper
No opponent; teachers follow set lines
Rhythm Heaven
No opponent exists.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
PaRappa the Rapper
Songs are fixed sequences
Rhythm Heaven
Cue patterns are fixed once heard.
PaRappa the Rapper leans a little harder on optimization, though the gap is small.
PaRappa the Rapper
Freestyle scoring quirks for Cool rank
Rhythm Heaven
Learning each minigame's rhythm is shallow and quick.
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.