ΔE 22.2, loose: different enough that you should pick on purpose. Cockpit Green (IJN) is a little lighter, much more muted, cooler than Nurgling Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Cockpit Green (IJN) is a little lighter, much more muted, cooler than Nurgling Green.
The same difference applies the other way round: Nurgling Green is a little darker, much 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.
See Nurgling Green on the colour wheel See Cockpit Green (IJN) on the colour wheel
All matches: Nurgling Green equivalents · Cockpit Green (IJN) equivalents