head to head
The Elder Scrolls V: Skyrim - Special Edition asks more than Portal, and the gap is variance.

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

Optimization · Pure Optimization
An open world where build optimisation dissolves every combat challenge.
Portal leans Optimization (Pure Optimization); The Elder Scrolls V: Skyrim - Special Edition leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Portal
Portal placement timing modest.
The Elder Scrolls V: Skyrim - Special Edition
Combat timing matters little; difficulty bends to your build
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 Elder Scrolls V: Skyrim - Special Edition
Draugr and dragons run scripted AI packages
The Elder Scrolls V: Skyrim - Special Edition leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
The Elder Scrolls V: Skyrim - Special Edition
Loot rolls and radiant quests add minor mapped randomness
Portal leans a little harder on optimization, though the gap is small.
Portal
Pure puzzle-solving optimization.
The Elder Scrolls V: Skyrim - Special Edition
Perk, crafting and stealth-archer loops trivially solve combat
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.