ΔE 7.5, close: similar, with a visible difference side by side. Archaic Sepia Wash is a little lighter, warmer than Howling Sand. They are different kinds of paint: Army Painter Howling Sand is a one-coat contrast-style paint and Two Thin Coats Archaic Sepia Wash is a wash/shade, 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). Archaic Sepia Wash is a little lighter, warmer than Howling Sand. They are different kinds of paint.
The same difference applies the other way round: Howling Sand is a little darker, 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 Howling Sand on the colour wheel See Archaic Sepia Wash on the colour wheel
All matches: Howling Sand equivalents · Archaic Sepia Wash equivalents