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
Space 4X where out-planning the galaxy's economy wins wars before they start.

Optimization · Pure Optimization
Long-horizon empire optimization over a randomly dealt but mappable map.
Galactic Civilizations II: Dread Lords leans Optimization (Pure Optimization); Sid Meier's Civilization 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.
Galactic Civilizations II: Dread Lords
Turn-based; zero dexterity
Sid Meier's Civilization
Turn-based clicking, zero physical demand
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Galactic Civilizations II: Dread Lords
Acclaimed AI still follows mappable doctrines
Sid Meier's Civilization
AI leaders follow mappable personalities, not adaptive minds
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Galactic Civilizations II: Dread Lords
Galaxy generation and unexplored starts
Sid Meier's Civilization
Map generation and combat rolls hide early information
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Galactic Civilizations II: Dread Lords
Economy sliders, ship design, and expansion math dominate
Sid Meier's Civilization
Tech routing, expansion and economy are deeply solvable
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.