How can you tell the difference between a Siberian Cat and a Maine Coon species of cat?

I have a friend with a beautiful cat named Tucker she told me too find out his breed online I thought he was a Siberian of the Lynx variety, white mane, tufted ear, loves water, extremely loyal, nearly 5 foot vertical jump, and he is huge and at just a little over a year old, after researching online we began calling him a Siberian. However the vet says she thinks he's a Maine Coon anyway to tell the difference?