In the example below FirstNumber and SecondNumber are method parameters where as FN and LN are method arguments. The method DEFINITION specifies the names and types of any parameters that are required. When calling code CALLS the method, it provides concrete values CALLED arguments for each parameter. The arguments must be compatible with the parameter type but the argument name (if any) used in the calling code does not have to be the same as the parameter named defined in the method.

using System;
namespace Demo
{
class Program
{
public static void Main()
{
int FN = 10;
int SN = 20;
//FN and LN are method arguments
int TOTAL = Sum(FN, SN);
Console.WriteLine(Total);
}
//FirstNumber and SecondNumber are method parameters
public static int Sum(int FirstNumber, int SecondNumber)
{
int Result = FirstNumber + SecondNumber;
return Result;
}
}
}

In the example below FirstNumber and SecondNumber are method parameters where as FN and LN are method arguments. The method definition specifies the names and types of any parameters that are required. When calling code calls the method, it provides concrete values called arguments for each parameter. The arguments must be compatible with the parameter type but the argument name (if any) used in the calling code does not have to be the same as the parameter named defined in the method.

using System;
namespace Demo
{
class Program
{
public static void Main()
{
int FN = 10;
int SN = 20;
//FN and LN are method arguments
int Total = Sum(FN, SN);
Console.WriteLine(Total);
}
//FirstNumber and SecondNumber are method parameters
public static int Sum(int FirstNumber, int SecondNumber)
{
int Result = FirstNumber + SecondNumber;
return Result;
}
}
}