What is the difference between a publisher's frontlist and backlist?

In publishing, a frontlist is a list of a publisher's newly published book titles. A backlist is a list of a publisher's older books. The backlist is usually a book that is off the bestseller list and has been in print for more than a year. The interviewer wants to see that you understand these terms, which are pretty basic in the publishing industry. Keep your answer simple and, if possible, give specific examples from books that are currently on the HarperCollins frontlist and backlist.