Graveyard Earth vs Leather Brown

How close are they?

ΔE 7.3, close: similar, with a visible difference side by side. Leather Brown is a little darker than Graveyard Earth.

Can I use Leather Brown instead of Graveyard Earth?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Leather Brown is a little darker than Graveyard Earth.

Can I use Graveyard Earth instead of Leather Brown?

The same difference applies the other way round: Graveyard Earth is a little lighter.

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.