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

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Optimization · Pure Optimization
A two-player co-op puzzle game solved entirely by describing what you see over voice.
Portal leans Optimization (Pure Optimization); We Were Here leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
We Were Here
Walking and talking; no dexterity test
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.
We Were Here
Your partner cooperates rather than opposes
We Were Here leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
We Were Here
Each player sees only half the puzzle's information
Portal leans clearly harder on optimization.
Portal
Pure puzzle-solving optimization.
We Were Here
Puzzles have fixed solutions once communicated
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.