ΔE 14.3, fair: the same colour family, but not a straight swap. Green Gold is a little lighter, more saturated than Nurgle's Rot. They are different kinds of paint: Citadel Nurgle's Rot is a technical paint or medium and Golden Green Gold is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Green Gold is a little lighter, more saturated than Nurgle's Rot. They are different kinds of paint.
The same difference applies the other way round: Nurgle's Rot is a little darker, more muted.
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 Nurgle's Rot on the colour wheel See Green Gold on the colour wheel
All matches: Nurgle's Rot equivalents · Green Gold equivalents