Purple Tone vs Andalusian Earth

How close are they?

ΔE 51.6, loose: different enough that you should pick on purpose. Andalusian Earth is noticeably lighter, much more muted, warmer than Purple Tone.

Can I use Andalusian Earth instead of Purple Tone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 52). Andalusian Earth is noticeably lighter, much more muted, warmer than Purple Tone.

Can I use Purple Tone instead of Andalusian Earth?

The same difference applies the other way round: Purple Tone is noticeably darker, much 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.