head to head
Rainbow Six Siege asks more than Insurgency, and the gap is reads.

Execution · Competitive PvP
Hardcore team shooter where one bullet kills and the HUD tells you nothing.

Reads · Grand Arena
A tactical breach-and-defend shooter driven by mind games over angles and gadgets.
Insurgency leans Execution (Competitive PvP); Rainbow Six Siege leans Reads (Grand Arena).
Insurgency leans a little harder on execution, though the gap is small.
Insurgency
One-shot lethality rewards precise aim
Rainbow Six Siege
Crisp aim required but TTK is unforgiving.
Rainbow Six Siege leans clearly harder on reads.
Insurgency
Human squads flank and adapt each round
Rainbow Six Siege
Defenders adapt holds; attackers fake and bait.
Insurgency leans a little harder on variance, though the gap is small.
Insurgency
No killcam or HUD hides enemy positions
Rainbow Six Siege
Site rotations only; loadouts deterministic.
Rainbow Six Siege leans clearly harder on optimization.
Insurgency
Loadout points and objective route knowledge
Rainbow Six Siege
Operator picks, gadget placement, and utility usage.
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.