Grey Seer vs Moonstone Grey

How close are they?

ΔE 6.2, close: similar, with a visible difference side by side. Moonstone Grey is a little darker, more muted than Grey Seer.

Can I use Moonstone Grey instead of Grey Seer?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Moonstone Grey is a little darker, more muted than Grey Seer.

Can I use Grey Seer instead of Moonstone Grey?

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