ΔE 11.2, fair: the same colour family, but not a straight swap. Burnt Umber is noticeably lighter, more muted, warmer than Black Brown.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Burnt Umber is noticeably lighter, more muted, warmer than Black Brown.
The same difference applies the other way round: Black Brown is noticeably darker, 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 Black Brown on the colour wheel See Burnt Umber on the colour wheel
All matches: Black Brown equivalents · Burnt Umber equivalents