head to head
Call of Duty: Modern Warfare 2 asks more than Worms Clan Wars, and the gap is execution.

Execution · Competitive PvP
Blockbuster 2009 sequel famous for killstreak chains and frantic multiplayer.

Execution · Competitive PvP
Artillery aim and turn planning against human opponents on destructible terrain.
Call of Duty: Modern Warfare 2 leans Execution (Competitive PvP); Worms Clan Wars leans Execution (Competitive PvP).
Call of Duty: Modern Warfare 2 leans clearly harder on execution.
Call of Duty: Modern Warfare 2
Fast time-to-kill rewards raw aim and reflex
Worms Clan Wars
Grenade arcs and ninja-rope control decide turns
Call of Duty: Modern Warfare 2 leans a little harder on reads, though the gap is small.
Call of Duty: Modern Warfare 2
Outguessing human rotations and flanks
Worms Clan Wars
Anticipating human opponents' target priorities matters in clan play
Worms Clan Wars leans a little harder on variance, though the gap is small.
Call of Duty: Modern Warfare 2
Spawn flips and killstreak randomness
Worms Clan Wars
Crate drops and terrain destruction add swing
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Modern Warfare 2
Killstreak economy, loadout and map knowledge
Worms Clan Wars
Weapon economy and positioning plans reward forethought
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.