ΔE 9.3, close: similar, with a visible difference side by side. Temple Stone is a little darker, more saturated than Grey Castle.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Temple Stone is a little darker, more saturated than Grey Castle.
The same difference applies the other way round: Grey Castle 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.
See Grey Castle on the colour wheel See Temple Stone on the colour wheel
All matches: Grey Castle equivalents · Temple Stone equivalents