head to head
Call of War asks more than Hearts of Iron IV, and the gap is reads.

Optimization · Mind & Math
A slow WW2 grand-strategy of economy management against scheming human nations.

Optimization · Pure Optimization
WWII grand strategy: templates, production, and focus paths.
Call of War leans Optimization (Mind & Math); Hearts of Iron IV leans Optimization (Pure Optimization).
Hearts of Iron IV leans a little harder on execution, though the gap is small.
Call of War
Issuing orders is trivial; no twitch dimension
Hearts of Iron IV
pausable, micromanagement-heavy
Call of War leans clearly harder on reads.
Call of War
Human players form alliances and bluff in real time
Hearts of Iron IV
PvP partly, mostly scripted AI
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Call of War
Fog of war hides enemy unit positions and plans
Hearts of Iron IV
focus tree branches, events
Hearts of Iron IV leans a little harder on optimization, though the gap is small.
Call of War
Economy, research and unit composition decide the war
Hearts of Iron IV
division templates and production solved
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.