head to head
Neither is simply harder - they are hard in different places. Portal demands more optimization; Yandere Simulator demands more variance.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.

Optimization · Pure Optimization
Planning eliminations around fixed NPC schedules in a stealth sandbox.
Portal leans Optimization (Pure Optimization); Yandere Simulator leans Optimization (Pure Optimization).
Portal leans a little harder on execution, though the gap is small.
Portal
Portal placement timing modest.
Yandere Simulator
Stealth timing matters; precision rarely decides outcomes
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Portal
No adversary modeling player.
Yandere Simulator
Students follow schedules, not adaptive minds
Yandere Simulator leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
Yandere Simulator
NPC routines are scripted-but-unknown until observed
Portal leans clearly harder on optimization.
Portal
Pure puzzle-solving optimization.
Yandere Simulator
Planning eliminations around fixed schedules is the core puzzle
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.