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

Optimization · Pure Optimization
Quiet side-scrolling journey piloting a land-ship across a dried-out sea.

Optimization · Practiced Mastery
An easygoing co-op Kirby about recruiting enemies as friends and combining their elemental powers.
FAR: Lone Sails leans Optimization (Pure Optimization); Kirby Star Allies leans Optimization (Practiced Mastery).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
FAR: Lone Sails
Light platforming and timely lever pulls
Kirby Star Allies
Very low difficulty, AI allies carry fights
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
FAR: Lone Sails
No opponent of any kind
Kirby Star Allies
Friend AI helps rather than opposes
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
FAR: Lone Sails
Mostly fixed obstacles, minor unknowns first run
Kirby Star Allies
Fixed layouts and bosses
FAR: Lone Sails leans a little harder on optimization, though the gap is small.
FAR: Lone Sails
Fuel management and ship-routine efficiency are the game
Kirby Star Allies
Friend-ability element combos solve puzzles
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.