So, all arguments which do not make different predictions are extensionally equal, but are not intensional. From the Wikipedia page:
Consider the two functions f and g mapping from and to natural numbers, defined as follows:
To find f(n), first add 5 to n, then multiply by 2.
To find g(n), first multiply n by 2, then add 10.
These functions are extensionally equal; given the same input, both functions always produce the same value. But the definitions of the functions are not equal, and in that intensional sense the functions are not the same.
So, all arguments which do not make different predictions are extensionally equal, but are not intensional. From the Wikipedia page: