Different between dot net 3.5/3.0/2.0 :

The following are the differences between 3.5 ,3.0 and 2.0

.net 3.0 is mainly used for windows development.

.net 3.5 is multi targeted - from dropdown to build the application in .net 3.0/3.5/2.0.

All 3 frameworks used the same CLR of 2.0 but new features implemented to support the dlinq or linq features.

.net 3.5 has good Designer experience, JavaScript debugging and IntelliSense features, and the ability to view and even step into the core .NET Framework code during debugging.

I would like to mention certain feature that was introduced in 2.0
- Generics
- Partial Class
- Membership Providers
- ADO.NET
to list a few.

With 3.5 we have a new set of framework to work with
- WCF
- WPF
- Windows WF
- LINQ
- ASP.NET AJAX
to list a few.

To be more precise we can simply say
framework 3.0 = 2.0 + (WCF/WPF/WF/LINQ)
So this means that the web based capabilities have been enhanced.

ASP.NET 3.5 Features.

1. Nested Master Pages.

2. Datapager Control.

3. Listview Control.

4.Silverlight.

5. Ajax

Net Framework 3.5 can have Some of New Fetures(c#)

1.Linq to Sql (liq to sql,linq to dataset,linq to xml,linq to entities,linq to objects etc)

2.Lambda Expression.

3.Annoymous Types.

4.Extenction Methods.

5.Paritial Methods.

6.Local type Varibles.

Asp.net

1.Datapager Control.

2.Listview Control

3.Ajax toolkit


ASP.NET 3.5 are detailed here: http://www.asp.net/downloads/vs2008/