head to head
Neither is simply harder - they are hard in different places. Heroes of Might and Magic IV demands more reads; The Elder Scrolls V: Skyrim demands more execution.

Optimization · Pure Optimization
A turn-based strategy game where building the optimal army and economy decides victory.

Optimization · Pure Optimization
An open-world RPG mostly about discovering and stacking exploitable progression systems.
Heroes of Might and Magic IV leans Optimization (Pure Optimization); The Elder Scrolls V: Skyrim leans Optimization (Pure Optimization).
The Elder Scrolls V: Skyrim leans clearly harder on execution.
Heroes of Might and Magic IV
no real-time physical skill needed
The Elder Scrolls V: Skyrim
Combat is forgiving; aim and timing rarely punish you.
Heroes of Might and Magic IV leans clearly harder on reads.
Heroes of Might and Magic IV
predicting human opponent strategy in PvP
The Elder Scrolls V: Skyrim
Enemy AI is scripted and exploitable; not adaptive.
Heroes of Might and Magic IV leans clearly harder on variance.
Heroes of Might and Magic IV
combat rolls and map resources random
The Elder Scrolls V: Skyrim
Loot tables and leveled lists inject mild randomness.
Heroes of Might and Magic IV leans a little harder on optimization, though the gap is small.
Heroes of Might and Magic IV
army building and economy near-solvable
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.