ΔE 15.2, loose: different enough that you should pick on purpose. Light Brown is a little darker, much 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 Light Brown 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 15). Light Brown is a little darker, much more saturated than Gore-Grunta Fur. They are different kinds of paint.
The same difference applies the other way round: Gore-Grunta Fur is a little lighter, 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 Gore-Grunta Fur on the colour wheel See Light Brown on the colour wheel
All matches: Gore-Grunta Fur equivalents · Light Brown equivalents