ΔE 16.4, loose: different enough that you should pick on purpose. Yellow Ink is much more muted than Flash Gitz Yellow. They are different kinds of paint: Citadel Flash Gitz Yellow is an opaque base/layer paint and Formula P3 Yellow Ink is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Yellow Ink is much more muted than Flash Gitz Yellow. They are different kinds of paint.
The same difference applies the other way round: Flash Gitz Yellow is much more saturated.
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 Flash Gitz Yellow on the colour wheel See Yellow Ink on the colour wheel
All matches: Flash Gitz Yellow equivalents · Yellow Ink equivalents