What's difference between PublishOptions.ExpectedStream and PublishOptions.Stream

[aDisplayName]

.NET Client 1.0.3

In class PublishOptions, what is the difference between ExpectedStream and Stream? I've tried both options, and based on the result, it will both throw Exceptions when the stream defined in ExpectedStream or Stream differs from the actual stream the server handles the pub message. The only difference I can found is:

• When using Stream, there will be no error detected by the server, but the check will be performed .NET Client between value of Stream and value of the stream name from the response, and an exception will be thrown by the .NET Client if it doesn't match.
• When using ExpectedStream, the response from server will indicates an error, and the exception will thrown by .NET Client directly.

So what is the rationale to provide both options, if the end results are the same to the .NET client?