There's speculation
wargs are just
wolves but a specific name for them. In FOTR, when the Fellowship are attacked by wolves at Caradhras, both "wolves" and "wargs" are used in the exchange.
However,
Gandalf makes it seem otherwise when the morning dawns, and he says, "It is as I feared. These are no ordinary wolves." The wargs are referred to as wolves, however, for most of the exchange, and Gandalf earlier calls one "Hound of
Sauron." He also cries, "
Naur dan i ngaurhoth!", which means "Fire against the wolf-horde!", though the root
gaur of course means werewolf.
This indicates wargs are under Sauron's command in two ways: Sauron was known as the "Lord of Werewolves", and the references above indicate Gandalf sees them as Sauron's "work". I don't think it means they are werewolves, but some speculate from Gandalf's language they are. This line of reasoning indicates wargs and werewolves are interchangeable, or at least wolves in this passage and werewolves are.
Conversely, it is also possible none of them are related, and Gandalf was using references to indicate these wargs were under Sauron's dominion and not necessarily to name them werewolves. So it could be simple as these wolves in particular were working for Sauron because they did not have the wills of normal wolves. The
Hobbits who wrote this would see them as wolves, of course, having not the words to describe them otherwise. Wargs in this passage are mentioned once most likely from knowledge gained later. Or a term for clarifying these wolves were not ordinary.
Regardless, the wolves' coming in the passage in question were recognized by Gandalf as the hand of Sauron. This could either mean he saw these wolves as wolves of Sauron or werewolves (which could be interchangeable depending on how you read into Gandalf's wording)... And this is only speculation!
Either way, it seems clear wargs at least were wolves under Sauron's control. And werewolves seem to be
evil in the same regard but speculated to be originated from fallen
Maiar just like
Huan has been speculated to be a
Maia.