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
Hardcore team shooter where one bullet kills and the HUD tells you nothing.

Execution · Competitive PvP
Basketball shot-timing and scheme-reading against human or scripted defenses.
Insurgency leans Execution (Competitive PvP); NBA 2K13 leans Execution (Competitive PvP).
Insurgency leans a little harder on execution, though the gap is small.
Insurgency
One-shot lethality rewards precise aim
NBA 2K13
Stick handles and shot release timing decide possessions
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Insurgency
Human squads flank and adapt each round
NBA 2K13
Online play is constant scheme and tendency reading
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Insurgency
No killcam or HUD hides enemy positions
NBA 2K13
Shot RNG and loose-ball physics add noise
NBA 2K13 leans a little harder on optimization, though the gap is small.
Insurgency
Loadout points and objective route knowledge
NBA 2K13
Playcalling, rosters and matchup exploits reward study
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.