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

Execution · Pure Mechanics
The modern Rock Band keeping plastic-instrument band night alive with a huge DLC library.
PaRappa the Rapper leans Execution (Pure Mechanics); Rock Band 4 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.
PaRappa the Rapper
Hitting button cues on beat is the whole game
Rock Band 4
Instrument accuracy remains the entire test
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
Rock Band 4
No adaptive opponent
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
Rock Band 4
Freestyle solos add slight improvisational looseness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
PaRappa the Rapper
Freestyle scoring quirks for Cool rank
Rock Band 4
Overdrive pathing and chart familiarity
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.