head to head
Neither is simply harder - they are hard in different places. New Star Manager demands more variance; Portal demands more execution.

Optimization · Pure Optimization
A soccer management sim about optimizing squad, finances and tactics over a career.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
New Star Manager leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
New Star Manager
Menu and tap input, no physical performance demand
Portal
Portal placement timing modest.
New Star Manager leans clearly harder on reads.
New Star Manager
AI opponents follow systems, not adaptive mind-modelling
Portal
No adversary modeling player.
New Star Manager leans clearly harder on variance.
New Star Manager
Match outcomes and events carry meaningful randomness
Portal
Deterministic chambers; no randomness.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
New Star Manager
Squad building, training and tactics are the solvable core
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.