ΔE 8.3, close: similar, with a visible difference side by side. Turquoise is a little lighter than Duck Blue.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Turquoise is a little lighter than Duck Blue.
The same difference applies the other way round: Duck Blue is a little darker.
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 Duck Blue on the colour wheel See Turquoise on the colour wheel
All matches: Duck Blue equivalents · Turquoise equivalents