Difference between String.Empty and ""?

Adding to what ashokbusybee corectly said, there are instances when you must use "", for example:

[DefaultValue("")]
public string MyStringProperty
{
    // Accessors
}

Try to put string.Empty there!

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 "";

The most fundamental difference is missing from all previous answers.

Look at the declaration of string.Empty;

public static readonly string Empty;

So, strictly speaking this is not a constant. This is a read-only field actually assigned to a constant.
In the sample you provide with your question, "" is an immediate constant, (created every time you place it in the code).
I compared the two for referential equivalence using object.ReferenceEquals -- they appeared to be the same, but nothing really guarantee that.

The difference between a constant and read-only field can sometimes be detected during run-time. In particular, this is a reason why string.Empty is not allowed in attribute constructor where an attribute is allowed -- unfortunately! (see Toli's Answer Difference between String.Empty and ""?[^]).

In nearly all other cases, using string.Empty is allowed and highly preferred.

I usually consider mixing any kind of immediate constants (by the way, see this) with code as unacceptable, but make exclusion for code samples and other ad-hoc works.

One advice tip for not using "" in comparisons: test static predicate string.IsNullOrEmpty(string).

Another advice would be using resources instead of constants, but this is not always practical/possible. In resources, empty strings can be allowed.

please see the following link

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

See this discussion[^] or
this[^].

The difference between string.Empty and "" is very small. String.empty will not create any object while "" will create a new object in the memory for the checking. Hence string.empty is better in memory management.