head to head
Neither is simply harder - they are hard in different places. Call of Duty: Modern Warfare 2 demands more execution; SCP: Secret Laboratory demands more variance.

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

Execution · Competitive PvP
Chaotic asymmetric rounds testing aim, facility knowledge and reading untrustworthy humans.
Call of Duty: Modern Warfare 2 leans Execution (Competitive PvP); SCP: Secret Laboratory 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
SCP: Secret Laboratory
Gunfights and SCP chases demand aim and movement
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Modern Warfare 2
Outguessing human rotations and flanks
SCP: Secret Laboratory
Human teams bluff, betray and negotiate constantly
SCP: Secret Laboratory leans clearly harder on variance.
Call of Duty: Modern Warfare 2
Spawn flips and killstreak randomness
SCP: Secret Laboratory
Random spawns, items and facility layout each round
Call of Duty: Modern Warfare 2 leans a little harder on optimization, though the gap is small.
Call of Duty: Modern Warfare 2
Killstreak economy, loadout and map knowledge
SCP: Secret Laboratory
Class knowledge, keycard routes and zone control reward mastery
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.