head to head
Neither is simply harder - they are hard in different places. Final Fantasy XII: Revenant Wings demands more variance; Portal demands more execution.

Optimization · Pure Optimization
A real-time strategy RPG spin-off following Vaan's airship adventures.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Final Fantasy XII: Revenant Wings leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Final Fantasy XII: Revenant Wings
minimal direct control, RTS-lite touch input
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.
Final Fantasy XII: Revenant Wings
scripted enemy AI, not adaptive
Portal
No adversary modeling player.
Final Fantasy XII: Revenant Wings leans clearly harder on variance.
Final Fantasy XII: Revenant Wings
some summon drop randomness
Portal
Deterministic chambers; no randomness.
Portal leans a little harder on optimization, though the gap is small.
Final Fantasy XII: Revenant Wings
party composition and gambit-like strategy
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.