Rlyeh Grey vs German Uniform

How close are they?

ΔE 6.9, close: similar, with a visible difference side by side. German Uniform is a little darker, more saturated than Rlyeh Grey.

Can I use German Uniform instead of Rlyeh Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). German Uniform is a little darker, more saturated than Rlyeh Grey.

Can I use Rlyeh Grey instead of German Uniform?

The same difference applies the other way round: Rlyeh Grey is a little lighter, more muted.

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.