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

Optimization · Pure Optimization
An economic engine puzzle about balancing production chains across island settlements.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Dawn of Discovery leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Dawn of Discovery
Pausable building keeps hands out of the equation
Portal
Portal placement timing modest.
Dawn of Discovery leans a little harder on reads, though the gap is small.
Dawn of Discovery
AI traders and rivals follow predictable scripts
Portal
No adversary modeling player.
Dawn of Discovery leans clearly harder on variance.
Dawn of Discovery
Island fertilities and resources are unknown until scouted
Portal
Deterministic chambers; no randomness.
Dawn of Discovery leans a little harder on optimization, though the gap is small.
Dawn of Discovery
Production chains and population-tier economics are the entire game
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.