head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

Optimization · Pure Optimization
Dungeon-crawling PS1 sequel built around DNA digivolution and grinding through randomized domains.

Optimization · Pure Optimization
Optimising a daily calendar and persona fusion economy against scripted turn-based combat.
Digimon World 2 leans Optimization (Pure Optimization); Persona 3 FES leans Optimization (Pure Optimization).
Persona 3 FES leans a little harder on execution, though the gap is small.
Digimon World 2
Turn-based dungeon crawling; no dexterity
Persona 3 FES
Menu-driven turn battles need no physical skill
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Digimon World 2
Fixed AI encounters only
Persona 3 FES
Shadow AI is scripted weakness-exploitation, never adaptive
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Digimon World 2
Random dungeon layouts and recruitment rolls
Persona 3 FES
Tartarus floors, shuffle cards and fusion outcomes are randomised
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Digimon World 2
DNA digivolving and party math are the whole game
Persona 3 FES
Social link scheduling and persona fusion are a solvable calendar
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.