Spectral Green vs Wild Green

How close are they?

ΔE 15.9, loose: different enough that you should pick on purpose. Wild Green is much more saturated, warmer than Spectral Green.

Can I use Wild Green instead of Spectral Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Wild Green is much more saturated, warmer than Spectral Green.

Can I use Spectral Green instead of Wild Green?

The same difference applies the other way round: Spectral Green is much more muted, 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.