head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is execution, and it is a single point.

Execution · Competitive PvP
Vietnam-era large-scale multiplayer shooter mixing infantry firefights with helicopters and jungle ambushes.

Execution · Competitive PvP
Hardcore team shooter where one bullet kills and the HUD tells you nothing.
Battlefield Vietnam leans Execution (Competitive PvP); Insurgency leans Execution (Competitive PvP).
Insurgency leans a little harder on execution, though the gap is small.
Battlefield Vietnam
Gunplay, vehicle handling, and helicopter piloting
Insurgency
One-shot lethality rewards precise aim
Insurgency leans a little harder on reads, though the gap is small.
Battlefield Vietnam
Human squads flank and contest objectives unpredictably
Insurgency
Human squads flank and adapt each round
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield Vietnam
Spawn waves and vehicle availability shuffle fights
Insurgency
No killcam or HUD hides enemy positions
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield Vietnam
Map control, loadouts, and ticket-bleed knowledge
Insurgency
Loadout points and objective route knowledge
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.