Bad Moon Yellow vs Olive Yellow

How close are they?

ΔE 26.9, loose: different enough that you should pick on purpose. Olive Yellow is noticeably darker, much more muted, cooler than Bad Moon Yellow.

Can I use Olive Yellow instead of Bad Moon Yellow?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 27). Olive Yellow is noticeably darker, much more muted, cooler than Bad Moon Yellow.

Can I use Bad Moon Yellow instead of Olive Yellow?

The same difference applies the other way round: Bad Moon Yellow is noticeably lighter, much more saturated, 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.