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

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

Optimization · Pure Optimization
Balancing social energies and economy in a simplified city-planning sandbox.
Portal leans Optimization (Pure Optimization); SimCity Societies leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
SimCity Societies
Placing buildings has no physical demand
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.
SimCity Societies
No opponent of any kind
SimCity Societies leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
SimCity Societies
Occasional events, otherwise deterministic simulation
Portal leans a little harder on optimization, though the gap is small.
Portal
Pure puzzle-solving optimization.
SimCity Societies
Balancing societal values and economy is the entire 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.