What are the similarities between Twilight and Harry Potter?

The only real similarity between the two series are the werewolves. However, the werewolves in the Twilight series are actually shape-shifters and follow very different rules to the ones in Harry Potter.

In Harry Potter the werewolves change at the full moon and only at the full moon. The transformation is very painful and all humanity is lost during the days as a wolf. To become a werewolf, another werewolves saliva and the victims blood. They are not automatically part of a pack, although can join one if they choose that lifestyle, and are completely shunned from the wizarding world who fear them. They are also mortal.

In Twilight they are shape-shifters who can become wolves whenever they please. They are born with this ability and it only occurs among teenagers when vampires are in the area. They form a pack (with an alpha and beta) and can hear each others thoughts. They also do not age until they imprint and age with the person they love. As they can change at will, their secret is very well kept from the world.