ΔE 15.1, loose: different enough that you should pick on purpose. IJA Gray is much more muted, cooler than Nurgling Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). IJA Gray is much more muted, cooler than Nurgling Green.
The same difference applies the other way round: Nurgling Green is 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 IJA Gray on the colour wheel
All matches: Nurgling Green equivalents · IJA Gray equivalents