There are some things that are more appropriate to a children's than an adult book but there's a huge overlapping area and most kids read an age group up anyway.
Terry PratchettSo much paperwork to read! So much paperwork to push away! So much paperwork to pretend he hadn't received and that might have been eaten by gargoyles.
Terry PratchettGods don't like people not doing much work. People who aren't busy all the time might start to think.
Terry Pratchett