head to head
SpaceChem asks more than World of Goo, and the gap is optimization.

Optimization · Pure Optimization
A hardcore programming-in-disguise puzzle where you wire atomic assembly lines to synthesize compounds.

Optimization · Pure Optimization
A physics puzzle game about building wobbly towers and bridges from living goo balls.
SpaceChem leans Optimization (Pure Optimization); World of Goo leans Optimization (Pure Optimization).
World of Goo leans a little harder on execution, though the gap is small.
SpaceChem
Drawing waldo paths requires no physical precision
World of Goo
Placing goo balls needs only mild precision
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
SpaceChem
No opponent; pure logic construction
World of Goo
No opponent exists
World of Goo leans a little harder on variance, though the gap is small.
SpaceChem
All reactor inputs are deterministic and fixed
World of Goo
Physics are visible and deterministic
SpaceChem leans clearly harder on optimization.
SpaceChem
Designing correct chemical pipelines that transform inputs to outputs exactly
World of Goo
Tower structure and goo economy are solvable per level
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.