Dark Ghost Gray vs Lavender Grey

How close are they?

ΔE 7.9, close: similar, with a visible difference side by side. Lavender Grey is a little darker than Dark Ghost Gray.

Can I use Lavender Grey instead of Dark Ghost Gray?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Lavender Grey is a little darker than Dark Ghost Gray.

Can I use Dark Ghost Gray instead of Lavender Grey?

The same difference applies the other way round: Dark Ghost Gray 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.