Difference between .NET 3.5 and .NET 4.0

	.NET 3.5	.NET 4.0
Definition	A version of .NET framework that preceded .NET 3.0	A version of .NET framework that preceded .NET 3.5
Direct Access to Client Data	No	Yes, using client data view and client data context objects
View State can be applied to the Control level	No	Yes, by using viewstate mechanism.
Permanent URL redirection	No	Yes, by using RedirectPermanent()
Size of installer	2.7 MB	869 KB
Enhanced features compared to previous versions	ASP.NET AJAX, Language Integrated Query (LINQ), enhanced Window Communication Foundation.	Improvements in CLR , BCL, data modeling, parallel programming, asp.net enhancements etc.
Output Caching	Yes, with limitation	Yes, easy to configure one or more custom output-cache providers.
Size of Web config file	Large due the Ajax, routing and integration with IIIS 7.	Can be empty or small as major configuration elements have been moved to the machine.config file.
Setting of Meta Tags	Two meta tags can be used- With name as keywords  With name as description	The keywords and meta tags can be included as part of page directive itself.
A control to  filter the data returns by EntitiyDataSource and LinqDataSource controls	Not present	Yes. QueryExtender Control
Hashing Algorithm	HMACSHA1	HMACSHA256