Feral Green vs Iosan Green

How close are they?

ΔE 21.3, loose: different enough that you should pick on purpose. Iosan Green is a little lighter, much more saturated than Feral Green.

Can I use Iosan Green instead of Feral Green?

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

Can I use Feral Green instead of Iosan Green?

The same difference applies the other way round: Feral Green is a little 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.