head to head
Neither is simply harder - they are hard in different places. Stellaris demands more reads; The Elder Scrolls V: Skyrim demands more execution.

Optimization · Pure Optimization
A grand strategy 4X where empire optimization carries you through random crises.

Optimization · Pure Optimization
An open-world RPG mostly about discovering and stacking exploitable progression systems.
Stellaris leans Optimization (Pure Optimization); The Elder Scrolls V: Skyrim leans Optimization (Pure Optimization).
The Elder Scrolls V: Skyrim leans clearly harder on execution.
Stellaris
Real-time pausable with no input precision.
The Elder Scrolls V: Skyrim
Combat is forgiving; aim and timing rarely punish you.
Stellaris leans clearly harder on reads.
Stellaris
AI is scripted; multiplayer adds modest adaptation.
The Elder Scrolls V: Skyrim
Enemy AI is scripted and exploitable; not adaptive.
Stellaris leans clearly harder on variance.
Stellaris
Galaxy gen, anomalies, and crises vary widely.
The Elder Scrolls V: Skyrim
Loot tables and leveled lists inject mild randomness.
Stellaris leans clearly harder on optimization.
Stellaris
Empire builds, fleet comps, and economy dominate.
The Elder Scrolls V: Skyrim
Skill stacking, enchant loops, and exploits are deeply solvable.
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.