Sand Golem vs Rotten Pus

How close are they?

ΔE 19.1, loose: different enough that you should pick on purpose. Rotten Pus is noticeably lighter, much more saturated than Sand Golem.

Can I use Rotten Pus instead of Sand Golem?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Rotten Pus is noticeably lighter, much more saturated than Sand Golem.

Can I use Sand Golem instead of Rotten Pus?

The same difference applies the other way round: Sand Golem is noticeably darker, much more muted.

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.