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.

Optimization · Pure Optimization
Colour-painting terrain puzzles that resolve to finding the intended solution.

Optimization · Practiced Mastery
Acrobatic puzzle-platformer where rewinding time turns every fatal mistake into a do-over.
Nihilumbra leans Optimization (Pure Optimization); Prince of Persia: The Sands of Time leans Optimization (Practiced Mastery).
Prince of Persia: The Sands of Time leans a little harder on execution, though the gap is small.
Nihilumbra
Some platforming timing, but forgiving throughout
Prince of Persia: The Sands of Time
Acrobatic platforming chains need timing; rewind softens failure
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Nihilumbra
Enemies cannot be fought or read, only avoided
Prince of Persia: The Sands of Time
Sand creatures attack on fixed cues
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Nihilumbra
Hand-designed puzzles with nothing random
Prince of Persia: The Sands of Time
Rewind power removes most consequence of surprise
Nihilumbra leans a little harder on optimization, though the gap is small.
Nihilumbra
Choosing which colour solves each terrain puzzle is the game
Prince of Persia: The Sands of Time
Route reading and dagger resource management solve each room
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.