ΔE 29.4, loose: different enough that you should pick on purpose. Black Wash is much more muted than Coelia Greenshade.
Can I use Black Wash instead of Coelia Greenshade?
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 29). Black Wash is much more muted than Coelia Greenshade.
Can I use Coelia Greenshade instead of Black Wash?
The same difference applies the other way round: Coelia Greenshade is 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.