ΔE 18.2, loose: different enough that you should pick on purpose. Spectral Blue is a little lighter, cooler than Stegadon Scale Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Spectral Blue is a little lighter, cooler than Stegadon Scale Green.
The same difference applies the other way round: Stegadon Scale Green is a little darker, 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.
See Stegadon Scale Green on the colour wheel See Spectral Blue on the colour wheel
All matches: Stegadon Scale Green equivalents · Spectral Blue equivalents