ΔE 14.7, fair: the same colour family, but not a straight swap. Fluorescent Green is a little lighter, much more saturated than Gutrippa Flesh. They are different kinds of paint: Citadel Gutrippa Flesh is a one-coat contrast-style paint and Tamiya Fluorescent Green 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 15). Fluorescent Green is a little lighter, much more saturated than Gutrippa Flesh. They are different kinds of paint.
The same difference applies the other way round: Gutrippa Flesh is a little darker, much 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 Gutrippa Flesh on the colour wheel See Fluorescent Green on the colour wheel
All matches: Gutrippa Flesh equivalents · Fluorescent Green equivalents