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
WWII grand strategy: templates, production, and focus paths.

Optimization · Pure Optimization
A survival strategy game about building a civilization while battling other players.
Hearts of Iron IV leans Optimization (Pure Optimization); War Selection leans Optimization (Pure Optimization).
War Selection leans a little harder on execution, though the gap is small.
Hearts of Iron IV
pausable, micromanagement-heavy
War Selection
Some real-time control but not twitch-focused.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Hearts of Iron IV
PvP partly, mostly scripted AI
War Selection
Human opponents in multiplayer require some prediction.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Hearts of Iron IV
focus tree branches, events
War Selection
Resource spawns and combat rolls add unpredictability.
Hearts of Iron IV leans a little harder on optimization, though the gap is small.
Hearts of Iron IV
division templates and production solved
War Selection
Base-building and civilization strategy 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.