ΔE 24.0, loose: different enough that you should pick on purpose. Black Wash is noticeably darker, much more muted than Nightroot Shade.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 24). Black Wash is noticeably darker, much more muted than Nightroot Shade.
The same difference applies the other way round: Nightroot Shade is noticeably lighter, much 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 Nightroot Shade on the colour wheel See Black Wash on the colour wheel
All matches: Nightroot Shade equivalents · Black Wash equivalents