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

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

Optimization · Practiced Mastery
A retro-styled turn-based RPG about two solstice warriors.
Final Fantasy XV leans Optimization (Practiced Mastery); Sea of Stars leans Optimization (Practiced Mastery).
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
Sea of Stars
Timed hits demand input precision.
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
Sea of Stars
Enemies are scripted.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Final Fantasy XV
Loot and ascension variance
Sea of Stars
Light combat randomness.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Final Fantasy XV
Ascension grid, magic crafting, party planning
Sea of Stars
Combo and resource planning reward 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.