Local Variable :
               The scope or lifetime of the local variable 
is with in a block or procedure..
Eg: DECLARE @Variable1

Global Variable :
                The scope or lifetime of the global 
variable throughout the execution of the program..
Eg: DECLARE @@Variable1

Local Variables are declared within the function main.

  main()
    {
       int a,b,c;(local variable declaration)

     }
Global variables are declared outside the function main.

int FACT(int);
main()
{
   Local variable declaration;
}

A global variable can be accessed by all functions. It is
initialized at the beginning of the program and is deleted
when the program shuts down. A local variable is isolated in
its function.