head to head
Neither is simply harder - they are hard in different places. Like a Dragon: Infinite Wealth demands more variance; Portal demands more execution.

Optimization · Pure Optimization
A turn-based JRPG carried by job, gear, and bond-routing optimization.

Optimization · Pure Optimization
The portal-gun puzzle game whose solutions are everything.
Like a Dragon: Infinite Wealth leans Optimization (Pure Optimization); Portal leans Optimization (Pure Optimization).
Portal leans clearly harder on execution.
Like a Dragon: Infinite Wealth
Turn-based with positioning, low input demand
Portal
Portal placement timing modest.
Like a Dragon: Infinite Wealth leans a little harder on reads, though the gap is small.
Like a Dragon: Infinite Wealth
Scripted enemies
Portal
No adversary modeling player.
Like a Dragon: Infinite Wealth leans clearly harder on variance.
Like a Dragon: Infinite Wealth
Drop and ability rolls
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.
Like a Dragon: Infinite Wealth
Job, gear, and bond routing rewarded
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.