head to head
Neither is meaningfully harder - they pose close to the same test. The widest gap is variance, and it is a single point.

Execution · Pure Mechanics
An asymmetric horror FPS letting you play marine, alien, or predator, each with wholly different abilities.

Execution · Practiced Mastery
A gritty WWII Call of Duty that introduced the Zombies mode.
Aliens versus Predator (1999) leans Execution (Pure Mechanics); Call of Duty: World at War leans Execution (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Aliens versus Predator (1999)
Fast aliens and panicked aim demand twitch reflexes
Call of Duty: World at War
Twitch gunfights in fast multiplayer lobbies
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Aliens versus Predator (1999)
Asymmetric multiplayer pits unlike species against each other
Call of Duty: World at War
Human opponents reward positioning prediction
Aliens versus Predator (1999) leans a little harder on variance, though the gap is small.
Aliens versus Predator (1999)
Motion-tracker dread and dark vents hide enemy positions
Call of Duty: World at War
Random lobbies, spawns, and zombie waves
Call of Duty: World at War leans a little harder on optimization, though the gap is small.
Aliens versus Predator (1999)
Mastering each species' tools and level knowledge
Call of Duty: World at War
Perk loadouts and map control are learnable
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.