head to head
Neither is simply harder - they are hard in different places. Portal demands more execution; Sherlock Holmes: Crimes & Punishments demands more variance.

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

Optimization · Pure Optimization
A detective adventure about gathering evidence and assembling deduction chains across six cases.
Portal leans Optimization (Pure Optimization); Sherlock Holmes: Crimes & Punishments leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
Sherlock Holmes: Crimes & Punishments
Minor minigames, no real dexterity ceiling
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.
Sherlock Holmes: Crimes & Punishments
Suspects are scripted, nothing adapts to you
Sherlock Holmes: Crimes & Punishments leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
Sherlock Holmes: Crimes & Punishments
Clues are hidden but fixed until discovered
Portal leans a little harder on optimization, though the gap is small.
Portal
Pure puzzle-solving optimization.
Sherlock Holmes: Crimes & Punishments
Deduction chains have correct solvable answers
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.