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
Gunpowder-era Total War blending empire management with line battles.

Optimization · Pure Optimization
Classical 4X with dynastic events and order economy.
Empire: Total War leans Optimization (Pure Optimization); Old World leans Optimization (Pure Optimization).
Empire: Total War leans a little harder on execution, though the gap is small.
Empire: Total War
Real-time battle micro is modest
Old World
turn-based, no twitch
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Empire: Total War
Multiplayer line-battle feints exist
Old World
AI scripted, some MP
Old World leans a little harder on variance, though the gap is small.
Empire: Total War
Campaign AI and battle dice noise
Old World
event cards, character traits
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Empire: Total War
Campaign economy and line-infantry tactics are mappable
Old World
orders, families, tech routing
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.