head to head
Neither is harder. They score identically on all four axes, so the difference between them is in kind, not degree.

Execution · Practiced Mastery
Crisp NES licensed platformer about chipmunks hurling crates at robots.

Execution · Practiced Mastery
A handheld run-and-gun testing dodge precision and spawn memorisation.
Chip 'n Dale Rescue Rangers leans Execution (Practiced Mastery); Metal Slug Advance 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.
Chip 'n Dale Rescue Rangers
Tight jumps and box-throw timing
Metal Slug Advance
Dodging dense fire with one life bar demands precision
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Chip 'n Dale Rescue Rangers
Enemies are simple fixed patterns
Metal Slug Advance
Enemy soldiers spawn on strict scripts
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Chip 'n Dale Rescue Rangers
Deterministic levels
Metal Slug Advance
Card drops add light collection randomness
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Chip 'n Dale Rescue Rangers
Level memory and boss pattern knowledge
Metal Slug Advance
Memorising spawns and card abilities optimises every mission
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.