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
The last mainline Guitar Hero, wrapping its setlist in a quest with score power-ups.

Execution · Pure Mechanics
Pioneering rhythm game where a rapping dog believes his way through button-cue raps.
Guitar Hero: Warriors of Rock leans Execution (Pure Mechanics); PaRappa the Rapper 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.
Guitar Hero: Warriors of Rock
Expert charts and the brutal 2112 finale
PaRappa the Rapper
Hitting button cues on beat is the whole game
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Guitar Hero: Warriors of Rock
Nothing adapts
PaRappa the Rapper
No opponent; teachers follow set lines
PaRappa the Rapper leans a little harder on variance, though the gap is small.
Guitar Hero: Warriors of Rock
Deterministic charts
PaRappa the Rapper
Songs are fixed sequences
Guitar Hero: Warriors of Rock leans a little harder on optimization, though the gap is small.
Guitar Hero: Warriors of Rock
Power-up choices and star power routing
PaRappa the Rapper
Freestyle scoring quirks for Cool rank
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.