These downloads contain source code. Each is a complete sample that fully exercises Windows Azure Storage across blobs, queues, and tables.
The difference between the downloads is implementation approach.
Storage
DotNet
CS.zip is a .NET StorageClient library implementation in the C# language. This library come with the Windows Azure SDK. Contains helper classes for accessing blobs, queues, and tables.
Storage
REST
CS.zip is a REST implementation in the C# language. The code to implement REST calls includes retry logic. Contains helper classes for accessing blobs, queues, and tables; and for issuing REST calls with retry logic.
For a full storage implementation in PHP, see
http://phpazure.codeplex.com/.