ΔE 6.4, close: similar, with a visible difference side by side. Bright Green is a little darker, warmer than Weed Green.
Usually, if you are not matching paint already on the model. Close match (ΔE 6). Bright Green is a little darker, warmer than Weed Green.
The same difference applies the other way round: Weed Green is a little lighter, 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 Weed Green on the colour wheel See Bright Green on the colour wheel
All matches: Weed Green equivalents · Bright Green equivalents