head to head
Neither is simply harder - they are hard in different places. Classified: France '44 demands more reads; Fallout: New Vegas demands more execution.

Optimization · Pure Optimization
A turn-based WWII tactics game about optimizing squad positioning and ability sequences.

Optimization · Pure Optimization
A faction-driven RPG-shooter where build and route planning shape every ending.
Classified: France '44 leans Optimization (Pure Optimization); Fallout: New Vegas leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Classified: France '44
Turn-based, no manual aim or reflex demand
Fallout: New Vegas
Shooter inputs with VATS assist
Classified: France '44 leans clearly harder on reads.
Classified: France '44
Enemy AI is scripted, limited adaptive prediction
Fallout: New Vegas
Scripted factions and enemies
Classified: France '44 leans clearly harder on variance.
Classified: France '44
Hit chances and reinforcements add managed randomness
Fallout: New Vegas
Some loot and crit RNG
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Classified: France '44
Positioning, ability sequencing, and squad builds are the core
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
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.