ΔE 9.7, close: similar, with a visible difference side by side. Shield Brown is a little lighter than Sepia Tone. They are different kinds of paint: Army Painter Sepia Tone is a wash/shade and Reaper Shield Brown is an opaque base/layer 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 10). Shield Brown is a little lighter than Sepia Tone. They are different kinds of paint.
The same difference applies the other way round: Sepia Tone is a little darker.
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 Sepia Tone on the colour wheel See Shield Brown on the colour wheel
All matches: Sepia Tone equivalents · Shield Brown equivalents