ΔE 13.2, fair: the same colour family, but not a straight swap. Nurgling Green is more muted, warmer than Nuclear Sludge.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Nurgling Green is more muted, warmer than Nuclear Sludge.
The same difference applies the other way round: Nuclear Sludge is 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.
See Nuclear Sludge on the colour wheel See Nurgling Green on the colour wheel
All matches: Nuclear Sludge equivalents · Nurgling Green equivalents