Might be easier to show you an example of a silver snow ...here is my friends new boy Bill.
http://www.abooksigun-bengals.co.uk/bill.html If you look esp around his nose bridge, backs of ears and markings they are silver/grey. With a regular snow the points as they are called will be a warmer colour. When a regular snow gets older the points will go darker, normally a tan colour. Where as a silver snow they will have a lot less warmth.
Often the body markings are slightly more muted on a silver snow as it is masking the beige colour that is normally expressed in a regular snow.
To have a silver whether it is Silver (black) or Silver snow, Silver Blue, Silver Charcoal etc lol one parent must be Silver.