Think of it like basic algebra. X is the parameter that you have to fill in, and the number you place inside of it is the argument. So if you have an equation like X+2, X is your parameter, and any numbers you change for X become known as the arguments. So if using that equation you supplement 1 for x, you get 1+2. That means that 1 is an argument, supplied to the parameter of X.
Equally, if you have a function like dosomething("This"), it's definition would be dosomething(string parametername), but "This" would be the actual argument that is being supplied to the parameter, here named parametername.
In the simplest way to look at it, the parameter is the thing that the argument fills in, and the argument can be any number of things allowed by that parameter.
So it's a many-to-one relationship between Parameters and arguments, as you can have one parameter that can have many valid arguments, like our X+1 equation above. X can be any number known, and they are all valid.
