ΔE 7.3, close: similar, with a visible difference side by side. Underhive Ash is a little lighter, cooler than RAF Camouflage Beige (Hemp) BS381C/389.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Underhive Ash is a little lighter, cooler than RAF Camouflage Beige (Hemp) BS381C/389.
The same difference applies the other way round: RAF Camouflage Beige (Hemp) BS381C/389 is a little darker, warmer.
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 RAF Camouflage Beige (Hemp) BS381C/389 on the colour wheel See Underhive Ash on the colour wheel
All matches: RAF Camouflage Beige (Hemp) BS381C/389 equivalents · Underhive Ash equivalents