Wasteland Soil vs Liche Purple

How close are they?

ΔE 27.9, loose: different enough that you should pick on purpose. Liche Purple is noticeably darker, cooler than Wasteland Soil.

Can I use Liche Purple instead of Wasteland Soil?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 28). Liche Purple is noticeably darker, cooler than Wasteland Soil.

Can I use Wasteland Soil instead of Liche Purple?

The same difference applies the other way round: Wasteland Soil is noticeably lighter, warmer.

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.