Poxwalker vs Ancient Sepia

How close are they?

ΔE 18.8, loose: different enough that you should pick on purpose. Ancient Sepia is noticeably lighter, more muted, warmer than Poxwalker.

Can I use Ancient Sepia instead of Poxwalker?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Ancient Sepia is noticeably lighter, more muted, warmer than Poxwalker.

Can I use Poxwalker instead of Ancient Sepia?

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