Why is Harry Potter and Twilight series always compared?

[Sophia]

Well because they both have fiction similar stories

[Tasya]

I think because they were the first series that became phenomenon, that exploded in the market? Despite having different story and target audience, many people who read HP in their childhood grow with the series. As the result, when Twilight was released, it was also the DH release and the audience were much mature, so they find the switch from friendship to romance centered book is refreshing, so twilight became famous. So maybe that's why they are often compared, they are like the legends of YA literature.