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

Execution · Pure Mechanics
Arcade dogfighter about staying airborne amid swarming bullets on pure stick skill.

Execution · Pure Mechanics
A classic beat-em-up demanding execution against scripted enemy waves.
Luftrausers leans Execution (Pure Mechanics); Teenage Mutant Ninja Turtles III: The Manhattan Project leans Execution (Pure Mechanics).
Luftrausers leans a little harder on execution, though the gap is small.
Luftrausers
Momentum-based dogfighting demands constant precise control
Teenage Mutant Ninja Turtles III: The Manhattan Project
beat-em-up timing and enemy juggling
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Luftrausers
Enemy planes follow simple fixed behaviors
Teenage Mutant Ninja Turtles III: The Manhattan Project
enemies run simple fixed scripts
Luftrausers leans a little harder on variance, though the gap is small.
Luftrausers
Spawn patterns vary slightly
Teenage Mutant Ninja Turtles III: The Manhattan Project
minor enemy spawn randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Luftrausers
Part combos tweak the score game
Teenage Mutant Ninja Turtles III: The Manhattan Project
character choice and route memorization
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.