ΔE 30.7, loose: different enough that you should pick on purpose. Smoke Ink is noticeably lighter, much more muted than Purple Ink.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 31). Smoke Ink is noticeably lighter, much more muted than Purple Ink.
The same difference applies the other way round: Purple Ink is noticeably darker, 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 Purple Ink on the colour wheel See Smoke Ink on the colour wheel
All matches: Purple Ink equivalents · Smoke Ink equivalents