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

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

Optimization · Pure Optimization
Time-budgeted investigation that tests planning and routing under a real-time clock.
Portal leans Optimization (Pure Optimization); The Occupation leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
The Occupation
Sneaking inputs are simple; pressure comes from the clock
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.
The Occupation
Guards patrol on schedules, not adaptive minds
The Occupation leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
The Occupation
Document locations and guard timings are unknown first run
Portal leans a little harder on optimization, though the gap is small.
Portal
Pure puzzle-solving optimization.
The Occupation
Routing four real-time hours of investigation optimally is the test
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.