Squig Orange vs Fluorescent Red

How close are they?

ΔE 15.6, loose: different enough that you should pick on purpose. Fluorescent Red is a little lighter, much more saturated, cooler than Squig Orange. They are different kinds of paint: Citadel Squig Orange is an opaque base/layer paint and Golden Fluorescent Red is a fluorescent or effect paint, so they won’t behave the same on the model even where the colour is close.

Can I use Fluorescent Red instead of Squig Orange?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Fluorescent Red is a little lighter, much more saturated, cooler than Squig Orange. They are different kinds of paint.

Can I use Squig Orange instead of Fluorescent Red?

The same difference applies the other way round: Squig Orange is a little darker, much more muted, warmer.

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.