Moldy Ochre vs Bile Green

How close are they?

ΔE 39.2, loose: different enough that you should pick on purpose. Bile Green is noticeably lighter, much more saturated, cooler than Moldy Ochre.

Can I use Bile Green instead of Moldy Ochre?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 39). Bile Green is noticeably lighter, much more saturated, cooler than Moldy Ochre.

Can I use Moldy Ochre instead of Bile Green?

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