According to IndiaBIX's answers to ASP.NET interview questions:
The basic difference between ASP and ASP.NET is that ASP.NET is compiled whereas ASP is interpreted whereas. This implies that since ASP mainly uses VBScript, when an ASP page is executed, it is interpreted. On the other hand, ASP.NET uses.NET languages, such as C# and VB.NET, which are compiled to Microsoft Intermediate Language (MSIL).
Also see the section of the Wikipedia article that compares ASP.NET to ASP classic for a detailed comparison.
