ΔE 19.0, loose: different enough that you should pick on purpose. Ink Sepia is noticeably darker, more muted than Burnt Umber.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Ink Sepia is noticeably darker, more muted than Burnt Umber.
The same difference applies the other way round: Burnt Umber is noticeably lighter, 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 Burnt Umber on the colour wheel See Ink Sepia on the colour wheel
All matches: Burnt Umber equivalents · Ink Sepia equivalents