head to head
Supreme Commander asks more than Portal, and the gap is reads.

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

Optimization · Pure Optimization
Large-scale RTS famous for strategic zoom, thousand-unit armies, and a streaming mass-energy economy.
Portal leans Optimization (Pure Optimization); Supreme Commander leans Optimization (Pure Optimization).
Supreme Commander leans a little harder on execution, though the gap is small.
Portal
Portal placement timing modest.
Supreme Commander
Massive APM demands across strategic-zoom battlefields
Supreme Commander leans clearly harder on reads.
Portal
No adversary modeling player.
Supreme Commander
PvP hinges on scouting and countering opponent commitments
Supreme Commander leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
Supreme Commander
Deterministic engine; only unscouted intel
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Portal
Pure puzzle-solving optimization.
Supreme Commander
Streaming economy and build-order efficiency are the backbone
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.