ΔE 24.1, loose: different enough that you should pick on purpose. Hydromiel Yellow is noticeably lighter, more muted, cooler than Golden Griffon. They are different kinds of paint: Citadel Golden Griffon is an opaque base/layer paint and Green Stuff World Hydromiel Yellow 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 24). Hydromiel Yellow is noticeably lighter, more muted, cooler than Golden Griffon. They are different kinds of paint.
The same difference applies the other way round: Golden Griffon is noticeably darker, more saturated, 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.
See Golden Griffon on the colour wheel See Hydromiel Yellow on the colour wheel
All matches: Golden Griffon equivalents · Hydromiel Yellow equivalents