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

Execution · Competitive PvP
Destructible-environment shooter with tight gunplay.

Execution · Competitive PvP
Hardcore team shooter where one bullet kills and the HUD tells you nothing.
Battlefield: Bad Company 2 leans Execution (Competitive PvP); Insurgency leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Battlefield: Bad Company 2
Bullet drop and recoil demand real aim
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: Bad Company 2
Destruction and flanks punish positional reads
Insurgency
Human squads flank and adapt each round
Insurgency leans a little harder on variance, though the gap is small.
Battlefield: Bad Company 2
Some vehicle/spawn randomness, mostly skill
Insurgency
No killcam or HUD hides enemy positions
Battlefield: Bad Company 2 leans a little harder on optimization, though the gap is small.
Battlefield: Bad Company 2
Class kits and gadgets optimize objectives
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.