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

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

Optimization · Pure Optimization
An alchemy sim where mapping the potion-crafting system is the entire game.
Portal leans Optimization (Pure Optimization); Potion Craft leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
Potion Craft
no reflex skill, mostly menu-based crafting
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.
Potion Craft
customers aren't adaptive opponents
Potion Craft leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
Potion Craft
ingredient rolls add some unpredictability
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.
Potion Craft
potion-map navigation is a solvable system
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.