Difference between DotNet 1.0,2.0,3.0,4.0

DotNet 1.0 = Managed code.
DotNet 2.0 = Generics,ADO.NET.
DotNet 3.0 = Linq(Language Integarated Query),Partial Methods, VAR Keyword.
DotNet 3.5 = WPF,WCF,ASP.NET AJAX.
DotNet 4.0 = Dyanamic Programming.

DotNet 1.0 Understand It:

.Net managed code enjoy's benefits of CLR, which automatically checks for object scope and if it is not referenced by any object than it is removed from memory.

What is the difference between managed and unmanaged code?

Program written in any .net compatible language will go for
compilation for 2times.
In the first compilation of the program, the language
compiler will generate MSIL code which is the managed code. &

the code generated after the second execution ie by the CLR
is called unmanaged code which is machine understandable and
not by the user.

What is MSIL code ?

When the code is compiled, the compiler translates your code
into Microsoft intermediate language (MSIL). The common
language runtime includes a JIT compiler for converting this
MSIL then to native code.
MSIL contains metadata that is the key to cross language
interoperability. Since this metadata is standardized across
all .NET languages, a program written in one language can
understand the metadata and execute code, written in a
different language. MSIL includes instructions for loading,
storing, initializing, and calling methods on objects, as
well as instructions for arithmetic and logical operations,
control flow, direct memory access, exception handling, and
other operations.

DotNet 2.0: Generics,ASP.NET-AJAX.

DotNet 3.0: Understand It:

1.1-->Partial Methods(Refer:http://jalpesh.blogspot.com/2009/07/permanent-redirection-in-aspnet-40.html)

1.2-->LINQ stands for Language-Integrated Query. This means we can use any relational or XML-specific features to our programming languages and runtime. It is a general approach query and provide facilities to the .NET Framework to access any kind of sources of information, not just relational or XML data. It's a Language-Integrated Query to indicate that query is an integrated feature of the developer's primary programming languages (for example, Visual C#, Visual Basic). Language-integrated query allows query expressions to benefit from the rich metadata, compile-time syntax checking, static typing and IntelliSense that was previously available only to imperative code.

The format of the query is more or less simillar to that of SQL. The Select, From, Where clauses are also used here with the same meaning but in different style/location/position. Here is an example of a LINQ program.

using System;
using System.Linq;

class sample
{
static void Main()
{
int[] arrMarks = {78, 90, 56, 45, 89, 23, 67, 93};

IEnumerable Distinction = from m in arrMarks
where m > 70
orderby m
select m;

foreach (int distMark in Distinction)
MessageBox.Show(distMark.ToString());
}
}

DotNet 3.5 Understand It:

WPF = Windows Presentation Foundation.

WPF is the latest in desktop app development in .Net. It features markup based layout much like asp.net. The markup language is XAML. It provides a new way to develop desktop applications keeping UI and logic separate.

WCF = Window Communication Services

WCF is used to communicate between different applications with stuff like services. It is much like web services, but is much more robust and configuration enabled. WCF web services can be configured to act like asmx webservices, or use json or something else. Anything that represents a service can benefit from WCF, such as web services, windows services etc.

DotNet 4.0: Dyanamic Progamming

1.Named and Optional Parameters.(Refer:::http://jalpesh.blogspot.com/search/label/C%23.NET)
2.Integarated COM interop.
3.Co and Contra Variance(Used in interface and delegates).
4.Dyanamic Typed Objects.
5. Response.PermanentRedirect,Page.Keywords and Page.Description Properties for SEO
Refer(http://jalpesh.blogspot.com/2009/07/pagemetadescription-and.html)

Example For Dyanamic Keyword:
http://jalpesh.blogspot.com/2009/11/c-40-dynamic-data-type-difference.html