ΔE 10.1, fair: the same colour family, but not a straight swap. Fluor Blue is a little lighter, warmer than Imrik Blue. They are different kinds of paint: Citadel Imrik 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 10). Fluor Blue is a little lighter, warmer than Imrik Blue. They are different kinds of paint.
The same difference applies the other way round: Imrik Blue is a little darker, 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 Imrik Blue on the colour wheel See Fluor Blue on the colour wheel
All matches: Imrik Blue equivalents · Fluor Blue equivalents