ΔE 7.8, close: similar, with a visible difference side by side. Swamp Brown is more saturated than Gore-Grunta Fur. They are different kinds of paint: Citadel Gore-Grunta Fur is a one-coat contrast-style paint and Green Stuff World Swamp Brown 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 8). Swamp Brown is more saturated than Gore-Grunta Fur. They are different kinds of paint.
The same difference applies the other way round: Gore-Grunta Fur 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 Gore-Grunta Fur on the colour wheel See Swamp Brown on the colour wheel
All matches: Gore-Grunta Fur equivalents · Swamp Brown equivalents