http://www.c-sharpcorner.com/UploadFile/051e29/session-and-application-in-Asp-Net/
Session Object-This is handle particular session level information. Application Object-This is handle Entire Application level information.
What is the difference between Session Object and Application Object? PDF Print E-mail Thursday, 21 July 2011 18:28 Session object is used to store state specific information per client basis. It is specific to particular user. Application object is used to store data which available across the entire application and shared across multiple users sessions. Session has the expiration time,default time 20 mints.But application object doesn't have the expiration time. Session object is used to maintain the session of each user. If one user enter in to the application then they get seesion id if he leaves from the application then the session id is deleted.If they again enter in to the application they get different session id. But for application object the id is maintained for whole application.it doesn't differ for any user.