Bestial Green vs Deep Green

How close are they?

ΔE 20.3, loose: different enough that you should pick on purpose. Deep Green is noticeably darker, more saturated, cooler than Bestial Green.

Can I use Deep Green instead of Bestial Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Deep Green is noticeably darker, more saturated, cooler than Bestial Green.

Can I use Bestial Green instead of Deep Green?

The same difference applies the other way round: Bestial Green is noticeably lighter, 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.