Space Grey vs Light Gray

How close are they?

ΔE 6.9, close: similar, with a visible difference side by side. Light Gray is more muted than Space Grey.

Can I use Light Gray instead of Space Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Light Gray is more muted than Space Grey.

Can I use Space Grey instead of Light Gray?

The same difference applies the other way round: Space Grey is more saturated.

ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.