ΔE 11.7, fair: the same colour family, but not a straight swap. Fluor Rose is more saturated than Emperor's Children. They are different kinds of paint: Citadel Emperor's Children is an opaque base/layer paint and Green Stuff World Fluor Rose 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 Rose is more saturated than Emperor's Children. They are different kinds of paint.
The same difference applies the other way round: Emperor's Children is more muted.
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 Emperor's Children on the colour wheel See Fluor Rose on the colour wheel
All matches: Emperor's Children equivalents · Fluor Rose equivalents