Dry Blood vs Chestnut Brown

How close are they?

ΔE 16.5, loose: different enough that you should pick on purpose. Chestnut Brown is noticeably lighter, more muted than Dry Blood.

Can I use Chestnut Brown instead of Dry Blood?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Chestnut Brown is noticeably lighter, more muted than Dry Blood.

Can I use Dry Blood instead of Chestnut Brown?

The same difference applies the other way round: Dry Blood is noticeably darker, 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.