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

Optimization · Pure Optimization
Alternate-history RTS where economy management and build orders win wars.

Optimization · Mind & Math
Economy and formation optimisation at huge scale against adapting human strategy.
Command & Conquer: Red Alert leans Optimization (Pure Optimization); Cossacks: European Wars leans Optimization (Mind & Math).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Command & Conquer: Red Alert
Micro and base management under time pressure
Cossacks: European Wars
Managing thousands of units strains APM and attention
Cossacks: European Wars leans a little harder on reads, though the gap is small.
Command & Conquer: Red Alert
PvP skirmish rewards predicting enemy pushes
Cossacks: European Wars
Human opponents shift compositions and timing attacks
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Command & Conquer: Red Alert
Fog of war conceals army composition
Cossacks: European Wars
Map resources and scouting gaps hide information early
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Command & Conquer: Red Alert
Ore economy and build orders decide games
Cossacks: European Wars
Economy ratios, tech order and formation math dominate outcomes
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.