In general, I would say the sand on the beaches in Puerto Vallarta is not white and never equivalent to the ones in the Caribbean. There is a logical explanation for this, there are many coral reefs in the Gulf of Mexico and these when they die and erode become white sand. On the Pacific Ocean side, the ecosystem and deeper waters don’t sustain large reefs, so the sands are created by geological processes. Furthermore, beaches in Cancun are actually artificial and have to be filled up with trucks each time a hurricane washes them away, so what would you prefer, nice clear yellow natural sand beaches or the fake/artificial option? 😉
In any case, there are a variety of colours on the local beaches, I’ve noticed the lightest coloured ones are Playa de Oro and Flamingos (Nuevo Vallarta), the southern beaches tend to have a golden yellow colour and granulometry varies from medium-coarse to fine.
Romantic Zone Olas Altas Beach (before sunset), Puerto Vallarta, Jalisco, Mexico