ASP.NET Web Site vs ASP.NET Web Application [duplicate]

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Possible Duplicates:

What is the difference between web application and website in asp.net?

ASP.NET: Web Site or Web Application?

To start a new ASP.NET project in Visual Studio 2008 we are presented with two options to go about creating a website,you can either create it as a new ASP.NET Web Site(File > New Website > ASP.Net website) or an ASP.NET Web Application(File > New Project > ASP.net Web Application).

What's the difference between these two project types? Has got to do anything w开发者_StackOverflow社区ith the security or performance?

Im using Visual Web Developer 2008 Express edition.Does the Visual Studio Professional Edition have additional options to create ASP.Net Project?

Thank You