ΔE 10.2, fair: the same colour family, but not a straight swap. Prussian Blue Hue is a little darker, warmer than Thousand Sons Blue. They are different kinds of paint: Citadel Thousand Sons Blue is an opaque base/layer paint and Golden Prussian Blue Hue is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Prussian Blue Hue is a little darker, warmer than Thousand Sons Blue. They are different kinds of paint.
The same difference applies the other way round: Thousand Sons Blue is a little lighter, 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 Thousand Sons Blue on the colour wheel See Prussian Blue Hue on the colour wheel
All matches: Thousand Sons Blue equivalents · Prussian Blue Hue equivalents