ΔE 12.0, fair: the same colour family, but not a straight swap. Fluor Blue is warmer than Hoeth Blue. They are different kinds of paint: Citadel Hoeth Blue is an opaque base/layer paint and Green Stuff World Fluor Blue is a fluorescent or effect 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 12). Fluor Blue is warmer than Hoeth Blue. They are different kinds of paint.
The same difference applies the other way round: Hoeth Blue is 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 Hoeth Blue on the colour wheel See Fluor Blue on the colour wheel
All matches: Hoeth Blue equivalents · Fluor Blue equivalents