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
A fast arcade rail-shooter testing reflexes through surreal scrolling stages.

Execution · Pure Mechanics
A classic beat-em-up demanding execution against scripted enemy waves.
Space Harrier II leans Execution (Pure Mechanics); Teenage Mutant Ninja Turtles III: The Manhattan Project leans Execution (Pure Mechanics).
Space Harrier II leans a little harder on execution, though the gap is small.
Space Harrier II
reflex dodging in fast rail-shooter
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.
Space Harrier II
fixed enemy patterns, no adaptation
Teenage Mutant Ninja Turtles III: The Manhattan Project
enemies run simple fixed scripts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Space Harrier II
minimal randomness
Teenage Mutant Ninja Turtles III: The Manhattan Project
minor enemy spawn randomness
Teenage Mutant Ninja Turtles III: The Manhattan Project leans a little harder on optimization, though the gap is small.
Space Harrier II
little beyond memorizing enemy waves
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.
full breakdown
Space Harrier II →
full breakdown
Teenage Mutant Ninja Turtles III: The Manhattan Project →