Nurgling Green vs Flat Green

How close are they?

ΔE 15.5, loose: different enough that you should pick on purpose. Flat Green is a little darker, more muted, cooler than Nurgling Green.

Can I use Flat Green instead of Nurgling Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Flat Green is a little darker, more muted, cooler than Nurgling Green.

Can I use Nurgling Green instead of Flat Green?

The same difference applies the other way round: Nurgling Green is a little lighter, 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.