The two main classifications for books are non-fiction and fiction.
They both are books. Picture books do not have to be anything except pictures. There doesn't have to be a plot of any kind. A novel usually has a plot. Some picture books have character(s) and a plot. The only similarity is they are both books.
Books are either nonfiction (filled with facts) or fiction (stories.) Each of these groupings has many subsets.
A three of a kind always beats a two pair.
"Which kind of books is..." The verb has to agree with kind in number. It is a bit odd sounding to say "kind of books"...not wrong just odd. It seems to emphasize that you expect more than one type in the kind. You more often hear "Which kind of book is..."
text books
The word "books" has 2 morphemes: "book" (a free morpheme) and "-s" (a bound morpheme indicating plural).
Nonfiction books. Usually reference books like textbooks or research books.
horror books
The Miz likes adventure books and wrestling books.
The journal books 1,2, and 3 are full of information about supernatural beings and paranormal activities in the town.
Adam Gontier has never confirmed what kind of books he enjoys reading.
The kind of books that Mr. Chips reads are referred to as the psychological fiction.