Stormy Grey vs Medium Brown

How close are they?

ΔE 8.0, close: similar, with a visible difference side by side. Medium Brown is a little darker, more saturated than Stormy Grey.

Can I use Medium Brown instead of Stormy Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Medium Brown is a little darker, more saturated than Stormy Grey.

Can I use Stormy Grey instead of Medium Brown?

The same difference applies the other way round: Stormy 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.