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 · Mind & Math
The original historical RTS of advancing ages, booming economies, and rushing armies.

Optimization · Pure Optimization
Alternate-history RTS where economy management and build orders win wars.
Age of Empires leans Optimization (Mind & Math); Command & Conquer: Red Alert 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.
Age of Empires
APM and micro under pressure
Command & Conquer: Red Alert
Micro and base management under time pressure
Age of Empires leans a little harder on reads, though the gap is small.
Age of Empires
Scouting and countering human strategies
Command & Conquer: Red Alert
PvP skirmish rewards predicting enemy pushes
Age of Empires leans a little harder on variance, though the gap is small.
Age of Empires
Fog of war and map resources
Command & Conquer: Red Alert
Fog of war conceals army composition
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Age of Empires
Build orders and eco timing dominate
Command & Conquer: Red Alert
Ore economy and build orders decide games
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.