Argument vs Parameter?

What is the difference between argument and parameter?

It seems same but there is difference between parameter and argument. 

Parameter is variable in the declaration of function.

Argument is the actual value of this variable that gets passed to function.

See an example:

def test_function(abc):

     return abc

 

// Calling the function

test_function(100)

Here 'abc' is parameter and '100' is argument.