ΔE 16.8, loose: different enough that you should pick on purpose. Gorgon Brown is a little lighter, more saturated, warmer than Perylene Violet.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Gorgon Brown is a little lighter, more saturated, warmer than Perylene Violet.
The same difference applies the other way round: Perylene Violet is a little darker, more muted, 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 Perylene Violet on the colour wheel See Gorgon Brown on the colour wheel
All matches: Perylene Violet equivalents · Gorgon Brown equivalents