ΔE 17.5, loose: different enough that you should pick on purpose. Purple Ink is noticeably darker, more muted, cooler than Phoenician Purple. They are different kinds of paint: Citadel Phoenician Purple is an opaque base/layer paint and Reaper Purple Ink is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Purple Ink is noticeably darker, more muted, cooler than Phoenician Purple. They are different kinds of paint.
The same difference applies the other way round: Phoenician Purple is noticeably lighter, more saturated, warmer.
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 Phoenician Purple on the colour wheel See Purple Ink on the colour wheel
All matches: Phoenician Purple equivalents · Purple Ink equivalents