The term "flat signed" means the author has written their name and nothing else on the page; In the bookselling world, the term "autographed" does not mean signed but means that the document in question has been hand-written.

Are autographed books worth more?

Books signed with an autopen, or with a signature that has been added by the printers, for instance, have no added value. When a book contains a signature and nothing else, it's considered “signed”. ... With this last type, a dated signature is more valuable, with dates closer to publication being the most desirable.

Are signed books from Barnes and Noble Real?

The autographed books span many genres and interests and were signed by authors for Barnes & Noble customers. For more information, customers should visit or contact their local Barnes & Noble. ... Also available at list price are top authors across a wide variety of genres.