difffernce between int and int64 code example

Example 1: Int64

sbyte value1 = 124;
short value2 = 1618;
int value3 = Int32.MaxValue;

long number1 = value1;
long number2 = value2;
long number3 = value3;

Example 2: Int64

ulong ulNumber = 163245617943825;
try {
   long number1 = (long) ulNumber;
   Console.WriteLine(number1);
}
catch (OverflowException) {
   Console.WriteLine("{0} is out of range of an Int64.", ulNumber);
}

double dbl2 = 35901.997;
try {
   long number2 = (long) dbl2;
   Console.WriteLine(number2);
}   
catch (OverflowException) {
   Console.WriteLine("{0} is out of range of an Int64.", dbl2);
}
   
BigInteger bigNumber = (BigInteger) 1.63201978555e30;
try {
   long number3 = (long) bigNumber;
   Console.WriteLine(number3);
}
catch (OverflowException) {
   Console.WriteLine("{0} is out of range of an Int64.", bigNumber);
}    
// The example displays the following output:
//    163245617943825
//    35902
//    1,632,019,785,549,999,969,612,091,883,520 is out of range of an Int64.