Fall Green vs Toxic Yellow

How close are they?

ΔE 16.6, loose: different enough that you should pick on purpose. Toxic Yellow is a little lighter, much more muted, warmer than Fall Green.

Can I use Toxic Yellow instead of Fall Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Toxic Yellow is a little lighter, much more muted, warmer than Fall Green.

Can I use Fall Green instead of Toxic Yellow?

The same difference applies the other way round: Fall Green is a little darker, much more saturated, cooler.

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.