hi what the differnce between english mastiff and american mastiff,is it legal to mix these breeds for puppies,because i saw them advertised and was thinking of buying one.

As far as I am aware there is no such breed recognised as the American Mastiff, and why would anyone deliberately set out to cross breed them???  If you wnat a cross breed then go to a resuce kennel and give a dog a home, sadly there are a lot of bully crosses bred for macho reasons who then end up in rescue.  Don't encourage the breeding of more.

If you like Real Mastiffs then get yourself a well bred pedigree one with back up from a knowledgeable breeder.