ΔE 24.6, loose: different enough that you should pick on purpose. Bluebird Grey is noticeably darker, more muted than Violet Coven.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 25). Bluebird Grey is noticeably darker, more muted than Violet Coven.
The same difference applies the other way round: Violet Coven is noticeably lighter, 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 Violet Coven on the colour wheel See Bluebird Grey on the colour wheel
All matches: Violet Coven equivalents · Bluebird Grey equivalents