ΔE 8.5, close: similar, with a visible difference side by side. Abyssal Turquoise is a little lighter, more muted than Shadow Thorn.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Abyssal Turquoise is a little lighter, more muted than Shadow Thorn.
The same difference applies the other way round: Shadow Thorn is a little darker, 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 Shadow Thorn on the colour wheel See Abyssal Turquoise on the colour wheel
All matches: Shadow Thorn equivalents · Abyssal Turquoise equivalents