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

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

Optimization · Pure Optimization
A supernatural mystery adventure pairing a reluctant medium with a wisecracking ghost.
Portal leans Optimization (Pure Optimization); The Blackwell Legacy leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
The Blackwell Legacy
Pure conversation and clicking
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 Blackwell Legacy
No adaptive opponent
The Blackwell Legacy leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
The Blackwell Legacy
Clue connections unknown on first pass only
Portal leans a little harder on optimization, though the gap is small.
Portal
Pure puzzle-solving optimization.
The Blackwell Legacy
Fixed investigation chain; fully solvable with notes
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.