ΔE 7.9, close: similar, with a visible difference side by side. Heretic Turquoise is more saturated, warmer than Turnbull Turquoise.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Heretic Turquoise is more saturated, warmer than Turnbull Turquoise.
The same difference applies the other way round: Turnbull Turquoise is 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.
See Turnbull Turquoise on the colour wheel See Heretic Turquoise on the colour wheel
All matches: Turnbull Turquoise equivalents · Heretic Turquoise equivalents