ΔE 16.8, loose: different enough that you should pick on purpose. Arachnid Green is noticeably darker, more muted than Stegadon Scale Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Arachnid Green is noticeably darker, more muted than Stegadon Scale Green.
The same difference applies the other way round: Stegadon Scale Green is noticeably lighter, more saturated.
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 Arachnid Green on the colour wheel
All matches: Stegadon Scale Green equivalents · Arachnid Green equivalents