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
A focused Total War set in Viking-age Britain, trading scale for tighter kingdom management.
Empire: Total War leans Optimization (Pure Optimization); Total War Saga: Thrones of Britannia leans Optimization (Pure Optimization).
Total War Saga: Thrones of Britannia leans a little harder on execution, though the gap is small.
Empire: Total War
Real-time battle micro is modest
Total War Saga: Thrones of Britannia
Real-time battle micro matters in close fights
Empire: Total War leans a little harder on reads, though the gap is small.
Empire: Total War
Multiplayer line-battle feints exist
Total War Saga: Thrones of Britannia
Multiplayer battles involve some human prediction
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Empire: Total War
Campaign AI and battle dice noise
Total War Saga: Thrones of Britannia
Campaign events and AI moves add mild uncertainty
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
Total War Saga: Thrones of Britannia
Settlement planning and army composition decide the campaign
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.