According to [MSDN article][1]  there are some definition differences what is called parameter and what is called argument:

**Parameter:**
>A parameter represents a value that the procedure expects you to pass when you call it. The procedure's declaration defines its parameters.

**Argument:**
>An argument represents the value you pass to a procedure parameter when you call the procedure. The calling code supplies the arguments when it calls the procedure.

There is also a **great quote how to understand it in real-life** example:

>To communicate this information to the procedure, the procedure defines a parameter, and the calling code passes an argument to that parameter. You can think of the parameter as a parking place and the argument as an automobile. Just as different automobiles can park in the parking place at different times, the calling code can pass a different argument to the same parameter each time it calls the procedure.

  [1]: http://msdn.microsoft.com/en-us/library/9kewt1b3%28v=VS.80%29.aspx