head to head
Neither is simply harder - they are hard in different places. Call of Duty: Modern Warfare 2 demands more variance; Street Fighter II: The World Warrior demands more reads.

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

Execution · Competitive PvP
A test of precise inputs and constant human prediction across a fixed roster of matchup puzzles.
Call of Duty: Modern Warfare 2 leans Execution (Competitive PvP); Street Fighter II: The World Warrior leans Execution (Competitive PvP).
Street Fighter II: The World Warrior leans a little harder on execution, though the gap is small.
Call of Duty: Modern Warfare 2
Fast time-to-kill rewards raw aim and reflex
Street Fighter II: The World Warrior
Frame-precise inputs and combo timing define every matchup
Street Fighter II: The World Warrior leans clearly harder on reads.
Call of Duty: Modern Warfare 2
Outguessing human rotations and flanks
Street Fighter II: The World Warrior
Predicting human opponent's next move is constant and non-convergent
Call of Duty: Modern Warfare 2 leans clearly harder on variance.
Call of Duty: Modern Warfare 2
Spawn flips and killstreak randomness
Street Fighter II: The World Warrior
No meaningful RNG; match outcomes are skill-determined
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
Street Fighter II: The World Warrior
Character matchups and punish routes are learnable but not fully solvable
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.