head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

Optimization · Pure Optimization
WWII grand strategy: templates, production, and focus paths.

Optimization · Pure Optimization
A turn-based WWII dogfighting game about positioning planes and planning maneuvers.
Hearts of Iron IV leans Optimization (Pure Optimization); Sid Meier's Ace Patrol: Pacific Skies 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.
Hearts of Iron IV
pausable, micromanagement-heavy
Sid Meier's Ace Patrol: Pacific Skies
Turn-based moves, no twitch input
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
Sid Meier's Ace Patrol: Pacific Skies
Hot-seat multiplayer lets you predict human opponents
Sid Meier's Ace Patrol: Pacific Skies leans a little harder on variance, though the gap is small.
Hearts of Iron IV
focus tree branches, events
Sid Meier's Ace Patrol: Pacific Skies
Combat dice and positioning add chance
Hearts of Iron IV leans a little harder on optimization, though the gap is small.
Hearts of Iron IV
division templates and production solved
Sid Meier's Ace Patrol: Pacific Skies
Maneuver planning and upgrade choices solve each mission
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.