ΔE 29.5, loose: different enough that you should pick on purpose. Ink Sepia is noticeably darker, more muted, warmer than Night Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 30). Ink Sepia is noticeably darker, more muted, warmer than Night Blue.
The same difference applies the other way round: Night Blue is noticeably lighter, 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 Night Blue on the colour wheel See Ink Sepia on the colour wheel
All matches: Night Blue equivalents · Ink Sepia equivalents