Yellow Ochre vs Gun Corps Brown

How close are they?

ΔE 9.8, close: similar, with a visible difference side by side. Gun Corps Brown is a little darker, cooler than Yellow Ochre.

Can I use Gun Corps Brown instead of Yellow Ochre?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Gun Corps Brown is a little darker, cooler than Yellow Ochre.

Can I use Yellow Ochre instead of Gun Corps Brown?

The same difference applies the other way round: Yellow Ochre is a little 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.