ΔE 15.8, loose: different enough that you should pick on purpose. Red Oxide is noticeably darker, cooler than Gore-Grunta Fur. They are different kinds of paint: Citadel Gore-Grunta Fur is a one-coat contrast-style paint and Golden Red Oxide is an opaque base/layer 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). Red Oxide is noticeably darker, cooler than Gore-Grunta Fur. They are different kinds of paint.
The same difference applies the other way round: Gore-Grunta Fur is noticeably lighter, 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 Gore-Grunta Fur on the colour wheel See Red Oxide on the colour wheel
All matches: Gore-Grunta Fur equivalents · Red Oxide equivalents