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 Polyurethane Gloss Varnish 200 ml

Vallejo Surface Primer for Miniatures (Review and Tips) - Tangible Day

Vallejo Polyurethane Varnish - Satin, 5 Liter

Acrylic Varnish Gloss Medium 8oz - The Compleat Sculptor

This product protects painted models from dust and scratches, dirt and humidity Acrylic Varnish should never be applied until the paint has dried

Vallejo Gloss Varnish Polyurethane, 60ml

Vallejo Varnish Top Coat – USA Gundam Store

Gloss Varnish

Vallejo: Gloss Varnish (60ml)

Review: New Vallejo Game Color range – now for pro painters only