ΔE 6.2, close: similar, with a visible difference side by side. Flat Brown is more muted than Perylene Violet.
Usually, if you are not matching paint already on the model. Close match (ΔE 6). Flat Brown is more muted than Perylene Violet.
The same difference applies the other way round: Perylene Violet is more saturated.
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 Perylene Violet on the colour wheel See Flat Brown on the colour wheel
All matches: Perylene Violet equivalents · Flat Brown equivalents