ΔE 9.5, close: similar, with a visible difference side by side. Skullcrusher Brass is more muted than Greedy Gold.
Can I use Skullcrusher Brass instead of Greedy Gold?
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Skullcrusher Brass is more muted than Greedy Gold.
Can I use Greedy Gold instead of Skullcrusher Brass?
The same difference applies the other way round: Greedy Gold is more saturated.
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.