ΔE 8.8, close: similar, with a visible difference side by side. Bright Green is more saturated than Niblet Green.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Bright Green is more saturated than Niblet Green.
The same difference applies the other way round: Niblet Green is 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 Niblet Green on the colour wheel See Bright Green on the colour wheel
All matches: Niblet Green equivalents · Bright Green equivalents