head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Optimization · Pure Optimization
Fantasy 4X with strong asymmetric factions and quest paths.

Optimization · Pure Optimization
A turn-based strategy game where building the optimal army and economy decides victory.
Endless Legend leans Optimization (Pure Optimization); Heroes of Might and Magic IV 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.
Endless Legend
turn-based
Heroes of Might and Magic IV
no real-time physical skill needed
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Endless Legend
scripted AI, limited MP
Heroes of Might and Magic IV
predicting human opponent strategy in PvP
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Endless Legend
quest and tech rolls
Heroes of Might and Magic IV
combat rolls and map resources random
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Endless Legend
faction-specific yield optimization
Heroes of Might and Magic IV
army building and economy near-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.