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

Optimization · Pure Optimization
Solving a civilisation-scale resource and governance puzzle before an ecological deadline.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Eco leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Eco
No twitch element; all actions are build and craft clicks
Portal
Portal placement timing modest.
Eco leans clearly harder on reads.
Eco
Other players add mild human negotiation reads in multiplayer
Portal
No adversary modeling player.
Eco leans clearly harder on variance.
Eco
Meteor timer and ecosystem variables carry some hidden uncertainty
Portal
Deterministic chambers; no randomness.
Eco leans a little harder on optimization, though the gap is small.
Eco
Government systems, specialisation routing, and ecosystem management are richly 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.