Light Feldgrau vs Light Green Blue

How close are they?

ΔE 6.0, close: similar, with a visible difference side by side. Light Green Blue is more muted, cooler than Light Feldgrau.

Can I use Light Green Blue instead of Light Feldgrau?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Light Green Blue is more muted, cooler than Light Feldgrau.

Can I use Light Feldgrau instead of Light Green Blue?

The same difference applies the other way round: Light Feldgrau is more saturated, warmer.

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.