ΔE 51.4, loose: different enough that you should pick on purpose. Ink Blue is noticeably darker, more saturated, cooler than Brown Ink.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 51). Ink Blue is noticeably darker, more saturated, cooler than Brown Ink.
The same difference applies the other way round: Brown Ink is noticeably lighter, more muted, 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 Brown Ink on the colour wheel See Ink Blue on the colour wheel
All matches: Brown Ink equivalents · Ink Blue equivalents