Burnt Moss vs Akhelian Green

How close are they?

ΔE 21.1, loose: different enough that you should pick on purpose. Akhelian Green is a little lighter, much more saturated, cooler than Burnt Moss.

Can I use Akhelian Green instead of Burnt Moss?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Akhelian Green is a little lighter, much more saturated, cooler than Burnt Moss.

Can I use Burnt Moss instead of Akhelian Green?

The same difference applies the other way round: Burnt Moss is a little 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.