Leviathan Light vs Light Blue

How close are they?

ΔE 8.5, close: similar, with a visible difference side by side. Light Blue is a little darker, warmer than Leviathan Light.

Can I use Light Blue instead of Leviathan Light?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Light Blue is a little darker, warmer than Leviathan Light.

Can I use Leviathan Light instead of Light Blue?

The same difference applies the other way round: Leviathan Light is a little lighter, cooler.

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.