ΔE 62.3, loose: different enough that you should pick on purpose. Ink Sepia is noticeably darker, much more muted, warmer than Blue Ink.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 62). Ink Sepia is noticeably darker, much more muted, warmer than Blue Ink.
The same difference applies the other way round: Blue Ink is noticeably lighter, much more saturated, cooler.
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 Blue Ink on the colour wheel See Ink Sepia on the colour wheel
All matches: Blue Ink equivalents · Ink Sepia equivalents