ΔE 7.7, close: similar, with a visible difference side by side. Satin Varnish is a little darker than Primer White.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Satin Varnish is a little darker than Primer White.
The same difference applies the other way round: Primer White 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.
See Primer White on the colour wheel See Satin Varnish on the colour wheel
All matches: Primer White equivalents · Satin Varnish equivalents