C# is case-sensitive. Keywords are typed in the same case you will need to use in your code.

C++ is also case-sensitive

basic concepts of c sharp language

Object-oriented basics are far from basic. Every object-oriented language implements a subset of those things that make a good object-oriented language. And C#, distinct from C++,
Delphi, or Visual Basic 6 or Visual Basic.NET, has its own unique way of implementing these aspects of an object-oriented programming language (OOPL).
The tenets of object-oriented programming are encapsulation, inheritance, aggregation, and polymorphism. Languages that support these basic tenets are considered object-oriented languages. There is a diverse set of idioms and constructs that facilitate each of these tenets, including things like templates, operator overloading, interfaces, multithreading, multiple inheritance, exception handling, pointers, and garbage collection. C# is a powerful OOPL that supports the tenets of object-oriented programming by providing operator overloading,
inheritance, interfaces, exception handling, garbage collection, multiple interface inheritance, reflection, and multithreading. C# does not support templates, raw pointers, or multiple class inheritance. There is a lot of debate over whether or not these latter three features introduce more problems than they solve; for this reason they were left out of C#.
Instead of multiple inheritance, pointers, and templates, you do get additional new
features that will help you build Web applications and Web services. C# supports COM Interop, multilanguage programming, and rapid application development. There are a few trade-offs.
C# is managed code. The benefit is that you don’t have to worry about the slicing problem caused by bad pointers, and the garbage collector will help you avoid memory leaks. The trade-off is the relinquishment of raw pointers. Pointers support some advanced idioms, like reference-counted objects and access to all memory. This same access to any memory address provides ultimate control and responsibility. With power comes responsibility. (For raw pointers, you can still use unmanaged C++ code.)
C# is most like C++ in its grammar. Most of the everyday idioms you will use regularly in C# have the same syntax as C++, making the learning curve for C++ programmers the shallowest. Delphi and Java programmers will also find the transition to C# relatively easy, and even VB programmers will find a transition from VB to C# easier than from VB to C++.

C++ and Java programmers will feel right at home with the C# syntax, and Visual C++ programmers will appreciate the Visual Basic–like rapid application development supported by C# for Windows and the Web.