Light Gray Green vs Mossy Green

How close are they?

ΔE 9.2, close: similar, with a visible difference side by side. Mossy Green is a little lighter, more muted than Light Gray Green.

Can I use Mossy Green instead of Light Gray Green?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Mossy Green is a little lighter, more muted than Light Gray Green.

Can I use Light Gray Green instead of Mossy Green?

The same difference applies the other way round: Light Gray Green is a little darker, 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.