Scar Tissue vs Brutal Brown

How close are they?

ΔE 19.2, loose: different enough that you should pick on purpose. Brutal Brown is noticeably darker, warmer than Scar Tissue.

Can I use Brutal Brown instead of Scar Tissue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Brutal Brown is noticeably darker, warmer than Scar Tissue.

Can I use Scar Tissue instead of Brutal Brown?

The same difference applies the other way round: Scar Tissue is noticeably lighter, 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.