Tallarn Sand vs Warm Brown

How close are they?

ΔE 15.1, loose: different enough that you should pick on purpose. Warm Brown is noticeably darker, more muted, warmer than Tallarn Sand.

Can I use Warm Brown instead of Tallarn Sand?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Warm Brown is noticeably darker, more muted, warmer than Tallarn Sand.

Can I use Tallarn Sand instead of Warm Brown?

The same difference applies the other way round: Tallarn Sand is noticeably lighter, 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.