head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Optimization · Pure Optimization
The original post-apocalyptic CRPG where character builds solve the wasteland.

Optimization · Pure Optimization
JRPG that splits life between high-school calendars and climbing a tower of shadows.
Fallout leans Optimization (Pure Optimization); Persona 3 leans Optimization (Pure Optimization).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout
Turn-based, no dexterity
Persona 3
Turn-based combat needs no reflexes
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout
No adaptive opposition
Persona 3
Shadows follow fixed weakness scripts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout
To-hit rolls and random encounters
Persona 3
Tartarus floors and fusion inheritance rolls
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Fallout
SPECIAL builds and quest routing are deeply solvable
Persona 3
Calendar scheduling and persona fusion planning dominate
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.