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

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

Optimization · Pure Optimization
An idle dungeon crawler where you hire bar patrons and script teams to grind dungeons automatically.
Portal leans Optimization (Pure Optimization); Soda Dungeon leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Portal
Portal placement timing modest.
Soda Dungeon
Auto-combat does the fighting for you.
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.
Soda Dungeon
Dungeon monsters follow fixed behavior tables.
Soda Dungeon leans clearly harder on variance.
Portal
Deterministic chambers; no randomness.
Soda Dungeon
Loot rolls and dungeon events add meaningful luck.
Portal leans a little harder on optimization, though the gap is small.
Portal
Pure puzzle-solving optimization.
Soda Dungeon
Team scripts and gear economy decide run depth.
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.