ΔE 6.7, close: similar, with a visible difference side by side. Howling Sand is a little darker, warmer than Bright Green. They are different kinds of paint: AMMO by Mig Bright Green is an opaque base/layer paint and Army Painter Howling Sand is a one-coat contrast-style paint, so they won’t behave the same on the model even where the colour is close.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Howling Sand is a little darker, warmer than Bright Green. They are different kinds of paint.
The same difference applies the other way round: Bright 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 Bright Green on the colour wheel See Howling Sand on the colour wheel
All matches: Bright Green equivalents · Howling Sand equivalents