It's just that in Harry Potter the werewolves transform with the moon and don't keep their human mindset where as the Lycans in Underworld keep their human mindset while transformed and can transform at will. Lycans are what lucian is his mother was a werewolf who couldn't transform back but he was born in Human form therefore Lucian and anyone he turned could transform without needing the full moon and kept their Human minds even while transformed which is a huge advantage over Fenrir and his kind.