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

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

Execution · Competitive PvP
The 3D fighting series opener where execution and human mind-games decide every round.
Call of Duty: Modern Warfare 2 leans Execution (Competitive PvP); Tekken leans Execution (Competitive PvP).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Call of Duty: Modern Warfare 2
Fast time-to-kill rewards raw aim and reflex
Tekken
Frame-tight inputs, juggle combos, movement demand trained hands
Tekken leans clearly harder on reads.
Call of Duty: Modern Warfare 2
Outguessing human rotations and flanks
Tekken
Human opponent adapts; throws, lows, sidesteps form mixup mind-games
Call of Duty: Modern Warfare 2 leans clearly harder on variance.
Call of Duty: Modern Warfare 2
Spawn flips and killstreak randomness
Tekken
No hidden info; only matchup unfamiliarity early on
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
Tekken
Frame data, punishes, and combo routing are studyable systems
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.