ΔE 17.1, loose: different enough that you should pick on purpose. Red Leather is noticeably lighter, more saturated, warmer than Chestnut Brown.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Red Leather is noticeably lighter, more saturated, warmer than Chestnut Brown.
The same difference applies the other way round: Chestnut Brown is noticeably darker, more muted, 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 Chestnut Brown on the colour wheel See Red Leather on the colour wheel
All matches: Chestnut Brown equivalents · Red Leather equivalents