Please refer to the following URL to know the differences between ASP and ASP.NET,http://onlydifferencefaqs.blogspot.in/2012/08/aspnet-difference-faqs-3.html

ASP is scripting languages(vb script & java script) , this scripting languages arevinterpreter based ,this makes execution slow and no proper memory management.
ASP.NET supports .net languages VB.NET,C# this languages are compiler based errorfree code can be maintained for webpage,this makes execution faster and provides proper memory management.
ASP doesn't support serverside controls.
ASP.NET support serverside controls,this makes developer job easier and faster.
ASP doesn't support AJAX specification
ASP.NET supports AJAX specification

Following are some differences between ASP and ASP.NET:

• Better language support
• Programmable controls
• Event-driven programming
• XML-based components
• User authentication, with accounts and roles
• Higher scalability
• Increased performance - Compiled code
• Easier configuration and deployment
• Not fully ASP compatible...

Thanks!
Manoj(InfoAxon Technologies Limited)

ASP (Active Server Pages) and ASP.NET are both server side technologies for building web sites and web applications, ASP.NET is Managed compiled code - asp is interpreted. and ASP.net is fully Object oriented. ASP.NET has been entirely re-architected to provide a highly productive programming experience based on the .NET Framework, and a robust infrastructure for building reliable and scalable web
applications.”