ΔE 49.7, loose: different enough that you should pick on purpose. Violet Wash is noticeably lighter, much more saturated than Brown Grey Wash.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 50). Violet Wash is noticeably lighter, much more saturated than Brown Grey Wash.
The same difference applies the other way round: Brown Grey Wash is noticeably darker, much more muted.
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 Brown Grey Wash on the colour wheel See Violet Wash on the colour wheel
All matches: Brown Grey Wash equivalents · Violet Wash equivalents