Nurgling Green vs Gobi Brown

How close are they?

ΔE 19.4, loose: different enough that you should pick on purpose. Gobi Brown is noticeably darker, more muted, warmer than Nurgling Green.

Can I use Gobi Brown instead of Nurgling Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Gobi Brown is noticeably darker, more muted, warmer than Nurgling Green.

Can I use Nurgling Green instead of Gobi Brown?

The same difference applies the other way round: Nurgling Green is noticeably lighter, more saturated, 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.