ΔE 7.0, close: similar, with a visible difference side by side. Yellow Ink is more saturated than Pastel Yellow. They are different kinds of paint: Army Painter Pastel Yellow is a one-coat contrast-style 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.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Yellow Ink is more saturated than Pastel Yellow. They are different kinds of paint.
The same difference applies the other way round: Pastel Yellow 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 Pastel Yellow on the colour wheel See Yellow Ink on the colour wheel
All matches: Pastel Yellow equivalents · Yellow Ink equivalents