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

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

Optimization · Pure Optimization
A 1998 grand strategy game pitting Empire against Rebellion across a fog-shrouded galaxy.
Portal leans Optimization (Pure Optimization); Star Wars: Rebellion leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
Star Wars: Rebellion
Pausable grand strategy; no hands required
Star Wars: Rebellion leans clearly harder on reads.
Portal
No adversary modeling player.
Star Wars: Rebellion
Head-to-head play adds light human mind games
Star Wars: Rebellion leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
Star Wars: Rebellion
Fog of war and hidden agent missions conceal the galaxy
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.
Star Wars: Rebellion
Fleet logistics and mission scheduling reward systematic play
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.