Primer White vs Gloss Varnish

How close are they?

ΔE 6.6, close: similar, with a visible difference side by side. Gloss Varnish is a little darker than Primer White.

Can I use Gloss Varnish instead of Primer White?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Gloss Varnish is a little darker than Primer White.

Can I use Primer White instead of Gloss Varnish?

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.