Field Grey vs NATO Green

How close are they?

ΔE 7.3, close: similar, with a visible difference side by side. NATO Green is a little lighter, more saturated than Field Grey.

Can I use NATO Green instead of Field Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). NATO Green is a little lighter, more saturated than Field Grey.

Can I use Field Grey instead of NATO Green?

The same difference applies the other way round: Field Grey is a little darker, more muted.

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.