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

Optimization · Practiced Mastery
A real-time RPG carried by ascension-grid routing and magic crafting.

Optimization · Pure Optimization
A scripted RPG where pattern-learning and pacifist routing carry you.
Final Fantasy XV leans Optimization (Practiced Mastery); Undertale 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.
Final Fantasy XV
Real-time combat, modest input demand
Undertale
Bullet-hell dodging in scripted patterns
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Final Fantasy XV
Scripted enemies
Undertale
NPCs follow fixed dialogue trees, not adaptive
Final Fantasy XV leans a little harder on variance, though the gap is small.
Final Fantasy XV
Loot and ascension variance
Undertale
Minimal randomness in encounters
Undertale leans a little harder on optimization, though the gap is small.
Final Fantasy XV
Ascension grid, magic crafting, party planning
Undertale
Learning fixed boss patterns and mercy routes wins
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.