head to head
Neither is simply harder - they are hard in different places. Portal demands more optimization; Terra Feminarum demands more variance.

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

Optimization · Pure Optimization
A grand strategy game set in a fictional matriarchal world.
Portal leans Optimization (Pure Optimization); Terra Feminarum leans Optimization (Pure Optimization).
Portal leans a little harder on execution, though the gap is small.
Portal
Portal placement timing modest.
Terra Feminarum
light strategic-map movement control
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.
Terra Feminarum
AI factions follow fixed strategic logic
Terra Feminarum leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
Terra Feminarum
battle outcomes and events randomized
Portal leans clearly harder on optimization.
Portal
Pure puzzle-solving optimization.
Terra Feminarum
empire management and strategy dominate play
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.