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
A cinematic puzzle platformer about sneaking a hapless Mudokon past guards while rescuing his coworkers.
Nihilumbra leans Optimization (Pure Optimization); Oddworld: Abe's Oddysee leans Optimization (Practiced Mastery).
Oddworld: Abe's Oddysee leans a little harder on execution, though the gap is small.
Nihilumbra
Some platforming timing, but forgiving throughout
Oddworld: Abe's Oddysee
Precise platforming and stealth timing kill instantly
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
Oddworld: Abe's Oddysee
Sligs patrol on fixed scripts
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
Oddworld: Abe's Oddysee
Deterministic screens, no randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Nihilumbra
Choosing which colour solves each terrain puzzle is the game
Oddworld: Abe's Oddysee
Mudokon rescue routes and puzzle solutions are solvable
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.