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 run-and-gun arcade shooter that is almost pure twitch execution.

Execution · Pure Mechanics
A comedic reflex platformer testing jump timing against fast obstacles.
Metal Slug 5 leans Execution (Pure Mechanics); Montaro : RE leans Execution (Pure Mechanics).
Metal Slug 5 leans a little harder on execution, though the gap is small.
Metal Slug 5
precise dodge/shoot run-and-gun demands
Montaro : RE
Reflex jumping and timing carry this runner-platformer
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Metal Slug 5
enemy waves are fully scripted patterns
Montaro : RE
No adaptive opponent in a solo arcade game
Montaro : RE leans a little harder on variance, though the gap is small.
Metal Slug 5
minor drop and spawn randomness
Montaro : RE
Some procedural obstacles add randomness
Metal Slug 5 leans a little harder on optimization, though the gap is small.
Metal Slug 5
weapon pickup and route memorization
Montaro : RE
Little to solve beyond reacting to obstacles
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.