head to head
Neither is simply harder - they are hard in different places. Fallout: New Vegas demands more execution; NFL Head Coach 09 demands more reads.

Optimization · Pure Optimization
A faction-driven RPG-shooter where build and route planning shape every ending.

Optimization · Pure Optimization
An NFL management sim about roster building, scouting and game planning.
Fallout: New Vegas leans Optimization (Pure Optimization); NFL Head Coach 09 leans Optimization (Pure Optimization).
Fallout: New Vegas leans clearly harder on execution.
Fallout: New Vegas
Shooter inputs with VATS assist
NFL Head Coach 09
No on-field input; pure management interface
NFL Head Coach 09 leans clearly harder on reads.
Fallout: New Vegas
Scripted factions and enemies
NFL Head Coach 09
AI opponents scripted; light playcall prediction
NFL Head Coach 09 leans clearly harder on variance.
Fallout: New Vegas
Some loot and crit RNG
NFL Head Coach 09
Draft prospects, injuries and game sims carry hidden uncertainty
NFL Head Coach 09 leans a little harder on optimization, though the gap is small.
Fallout: New Vegas
Faction routing, perks, builds heavily rewarded
NFL Head Coach 09
Roster building, scouting and game planning are the whole game
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.