head to head
Neither is simply harder - they are hard in different places. Portal demands more execution; Wildlife Park demands more variance.

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

Optimization · Pure Optimization
A zoo-management sim about optimizing layout, economy and animal care.
Portal leans Optimization (Pure Optimization); Wildlife Park leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
Wildlife Park
Menu-driven building, no dexterity required
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.
Wildlife Park
No opponent, visitors follow scripted behavior
Wildlife Park leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
Wildlife Park
Some visitor and animal behavior randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Portal
Pure puzzle-solving optimization.
Wildlife Park
Layout, economy and animal care management is the game
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.