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

Optimization · Pure Optimization
Classic city builder about engineering the housing blocks and supply lines of ancient Egypt.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Pharaoh leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Pharaoh
Mouse-driven building at gentle pace
Portal
Portal placement timing modest.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Pharaoh
No adaptive opposition
Portal
No adversary modeling player.
Pharaoh leans clearly harder on variance.
Pharaoh
Occasional events and invasions, mostly predictable
Portal
Deterministic chambers; no randomness.
Pharaoh leans a little harder on optimization, though the gap is small.
Pharaoh
Walker logistics and city layout are deeply solvable
Portal
Pure puzzle-solving optimization.
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.