The Guardian has recently published an article about why American publishers sometimes change the titles of books. In fact they don't only change titles, they will also change names, places and spelling. The writer from The Guardian doesn't really have an answer to why this happens, but happen it does and can be confusing for library users - and librarians!
Outlander by Diana Gabaldon is a good example. It was originally published as Cross Stitch. Then there is The Northern Lights by Philip Pullman which became The Golden Compass, and Harry Potter and the Philosopher's Stone became Harry Potter and the Sorcerer's Stone. Looking at these titles, it is hard to understand why they were changed. It is a tricky business though, as often it can look like your favourite author has published a new book only to be met with disappointment when the story starts to feel very familiar!
When a new title is given to a book, our wonderful cataloguers always add an entry to the catalogue record that lets you know that the book has two titles.
Notes: Also published as: Cross stitch. London : Rowan, 1992.
Notes: Originally published as: Northern lights. London : Scholastic, 1995.
And whatever title you type in will take you to the correct book.