'I do,' Alice hastily replied; 'at least--at least I mean what I say--that's the same thing, you know.''Not the same thing a bit!' said the Hatter...
You might think 'book' is a rather basic term to include here. But not in publisher-speak. In fact, not in big-wide-world-speak, either.
If you tell someone you are writing a book, they will assume you mean a novel - and probably a novel for adults. That is not the definition of a book, but is a category of book. A book may also be intended for people of other ages, from babies to teenagers. It may be a bunch of lies (fiction) or all true (a non-fiction book). It may be a picture book, an academic text book, a school book, a book of jokes or puzzles or anecdotes, an anthology, a biography, an autobiography, a how-to book, a dictionary, a pop-up book, a coffee-table book, a colouring book.... there are lots of possibilities.
In publisher-speak a book may be any of these and, depending on the rights the publisher wishes to buy or grab, a CD, a Kindle book, a phone app, and the basis of a film, TV series, opera, theme park, set of merchandising or group of plushie toys. OK, the last don't count as the book, but you might find you've lost those when you thought you were selling a book.
The thing to look out for is the bit in the first paragraph where they define your book as 'the Work', thus making the IP (intellectual property) and the paperback or hardback book you are imagining one and the same thing. What do you mean by book? The physical object or the content? The problem is that 'book' is used in both senses and rarely does anyone specify which they mean. B is for Book should go alongside A is for Ambiguity.