What’s the grammatical difference?

Let's have a hypothetical example. A multiple choice question contains three pictures. One picture is of some books, and the question reads "Hon wa dore desu ka" (Which one is the books?). The books picture gets circled, and a sentence is written which reads "This one is the books". Is there any difference between: "Hon wa kore desu." and "Kore wa Hon desu." As I understand it, One says (lit.) "The books, this one is it/them" and the other reads "This one, it is/they are the books". Am I right, or is one of them wrong, and if so, why?

If the question is: "Hon wa dore desu ka?" then the answer should be "Hon wa kore desu" or "Kore GA hon desu."

"Hon wa kore desu" says "When it comes to books, it's THIS one," so that answers the question. Also, "Kore GA hon desu" says "It's THIS one that is books," so that also answers the question.

But "Kore wa hon desu" can only be an answer to a different question - someone pointing to a pile of books and asking "Kore wa nan desu ka" - to which you can say "Kore wa hon desu" ("When it comes to this, it's books.")