Parameters are variables in the function definition. Arguments are values you pass when calling. In int add(int a, int b), a and b are parameters. In add(5, 10), 5 and 10 are arguments.
The compiler matches arguments to parameters by position. First argument to first parameter, second to second. Wrong order gives wrong results or compile errors. Think of parameters as placeholders and arguments as real data.
The function defines slots, you fill them when calling.