Platinum is a natural white metal and weights 40% more than white gold as it is a denser metal.
To achieve ‘white gold’ yellow gold is mixed with other metals to make it whiter and is often plated with rhodium to achieve its shiny white surface. Over time white gold might begin to yellow and may require re-plating to regain its white colour.
Both platinum and gold can be scratched and neither are indestructible. Over time platinum develops a matte finish but if you prefer the high-finish look, regular polishing by a professional can maintain this finish.