Differece between "" and string.empty

There is no difference. They are equivalent.

There used to be a difference (before .NET 2.0), in that "" created a new, empty string object while String.Empty was a reference to a static instance of an emtpy string. This difference was removed .NET 2.0.

string.empty handles memory efficently than string x="";
"" actually creates an object but string.empty does not.
 
Also, it is a best practise to avoid hardcoding like "";

please see the following link
 
http://msdn.microsoft.com/en-us/library/system.string.empty%28v=VS.80%29.aspx

yes...

both are same.
the value of Strin.Emptyfield is the zero length string "".