head to head
Returnal asks more than Rain World, and the gap is execution.

Variance · Twitch Chaos
A brutal survival platformer where you are prey in a living, indifferent ecosystem.

Execution · Twitch Chaos
Bullet-hell roguelike third-person shooter.
Rain World leans Variance (Twitch Chaos); Returnal leans Execution (Twitch Chaos).
Returnal leans clearly harder on execution.
Rain World
Momentum-based movement and spear throws are slippery and demanding
Returnal
Bullet-hell dodge and aim under pressure
Returnal leans a little harder on reads, though the gap is small.
Rain World
Predator AI is dynamic simulation, not modeling of you
Returnal
Bosses scripted, patterns not adaptive
Same score on variance - which means the number cannot separate them. The difference is in what each one asks of you.
Rain World
Creature placement and behavior shift unpredictably each cycle
Returnal
Room layouts, parasites, items roguelike
Returnal leans a little harder on optimization, though the gap is small.
Rain World
Route knowledge and ecosystem mastery slowly tame the chaos
Returnal
Build synergies and route planning
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.