head to head
Hitman 2 (2018) asks more than Portal, and the gap is variance.

Optimization · Pure Optimization
More giant clockwork sandboxes where mapping NPC schedules is the real skill.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Hitman 2 (2018) leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans a little harder on execution, though the gap is small.
Hitman 2 (2018)
Minimal dexterity needed with a solid plan
Portal
Portal placement timing modest.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Hitman 2 (2018)
Clockwork NPC loops, nothing adapts
Portal
No adversary modeling player.
Hitman 2 (2018) leans clearly harder on variance.
Hitman 2 (2018)
Mission stories hidden until explored
Portal
Deterministic chambers; no randomness.
Hitman 2 (2018) leans a little harder on optimization, though the gap is small.
Hitman 2 (2018)
Routing, disguises, and unlocks converge on solved runs
Portal
Pure puzzle-solving optimization.
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.