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 · Practiced Mastery
Remake of the original Metroid with modern movement and a stealth epilogue.

Optimization · Practiced Mastery
Dimension-hopping spectacle platformer built on the classic arsenal-upgrade loop.
Metroid: Zero Mission leans Execution (Practiced Mastery); Ratchet & Clank: Rift Apart leans Optimization (Practiced Mastery).
Metroid: Zero Mission leans a little harder on execution, though the gap is small.
Metroid: Zero Mission
polished 2D movement plus a stealth finale
Ratchet & Clank: Rift Apart
Dodging, rift-tether mobility, and weapon aim.
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Metroid: Zero Mission
enemies and pirates are scripted
Ratchet & Clank: Rift Apart
Scripted enemies and setpieces only.
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Metroid: Zero Mission
hidden passages unknown only once
Ratchet & Clank: Rift Apart
Unknown encounters on first run.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Metroid: Zero Mission
sequence breaks and route optimization are celebrated
Ratchet & Clank: Rift Apart
Weapon leveling and bolt economy reward planned play.
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.