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
A football management sim about building squads and optimizing tactics against variance.

Optimization · Pure Optimization
A grand strategy 4X where empire optimization carries you through random crises.
Championship Manager 2008 leans Optimization (Pure Optimization); Stellaris leans Optimization (Pure Optimization).
Championship Manager 2008 leans a little harder on execution, though the gap is small.
Championship Manager 2008
Menu management requires no physical skill
Stellaris
Real-time pausable with no input precision.
Championship Manager 2008 leans a little harder on reads, though the gap is small.
Championship Manager 2008
Opponent AI tactics are somewhat predictable patterns
Stellaris
AI is scripted; multiplayer adds modest adaptation.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Championship Manager 2008
Match results and injuries carry significant randomness
Stellaris
Galaxy gen, anomalies, and crises vary widely.
Stellaris leans a little harder on optimization, though the gap is small.
Championship Manager 2008
Squad building, tactics and transfers are the deep core
Stellaris
Empire builds, fleet comps, and economy dominate.
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.