ΔE 17.6, loose: different enough that you should pick on purpose. Charred Brown is noticeably lighter, cooler than Dark Umber.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Charred Brown is noticeably lighter, cooler than Dark Umber.
The same difference applies the other way round: Dark Umber is noticeably darker, 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 Dark Umber on the colour wheel See Charred Brown on the colour wheel
All matches: Dark Umber equivalents · Charred Brown equivalents