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
WWI conquest shooter with weighty gunplay.

Execution · Competitive PvP
Hardcore team shooter where one bullet kills and the HUD tells you nothing.
Battlefield 1 leans Execution (Competitive PvP); Insurgency leans Execution (Competitive PvP).
Insurgency leans a little harder on execution, though the gap is small.
Battlefield 1
Bolt-actions reward steady aim and timing
Insurgency
One-shot lethality rewards precise aim
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield 1
Trench flanks and gas plays beat predictions
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 1
Behemoth spawns and chaos shift matches
Insurgency
No killcam or HUD hides enemy positions
Battlefield 1 leans a little harder on optimization, though the gap is small.
Battlefield 1
Class kits and vehicle counters matter
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.