Difference between Vallejo polyurethane & acrylic gloss varnish

AFAIK, the difference is that the polyurethane varnish is more durable & dries quicker. But can the polyurethane varnish be thinned with water or acrylic thinners? Does it yellow or brush well?

Vallejo Varnish Top Coat – USA Gundam Store

Matte Versus Gloss Varnishes for Miniatures and Models (Overview

Varnishes – Turbo Dork

Vallejo: Matt Acrylic Varnish (500ml), Accessories

What's the difference between Model - Acrylicos Vallejo

29650 Gloss Polyurethane Varnish 5L (5000ml)

Testing 41 Polymer Clay Sealers - The Blue Bottle Tree

Polyurethane Varnish Satin

Vallejo Acrylic and Polyurethane Varnish Gloss Matte or Satin

Paints, Supplies & Accessories - Vallejo - Kingdom of the Titans

Acrylic aerosol varnish is useful for quick and easy protection. The product does not contain toluene, and is ozone friendly.

Vallejo: Spray - Acrylic Gloss Varnish (400ml)