A difference is not what we're talking about here. To the person who just transported, there is no difference. He has all the memories and is identical to the person who dematerialized moments ago - it makes no difference to him.
But the guy who dematerialized? He's dead.
If I break a cake down into flour, butter, sugar, and eggs... then rebake them into an identical cake, there is no difference
, but they are not the same cake.
Consisting of the same matter does not make you the same person. There may be water molecules in me that used to be part of a tyrannosaurus, yet I am not part tyrannosaurus.