When I say neat piles, I mean, you know, if they are all tidily in one physical space. I am quite territorial over my books.

But when I say they are jumbled, I mean they are not organised. They are put in those piles in any order or category. The only order is a physical one, mandated by size and alignment. This is a useful order - physical volume and alignment - sicne it helps you put as many books as possible in a space, and also ensures that they are not falling out everytime you open a cupboard, and it also means that pages don't get dented. (all of these has happened to me.)

But Terry Pratchett's The Light Fantastic is miles away from The Colour of Magic. Right now it's lodged over Abha Daweswar's Babyji and under Don Delilo's Underworld. (Which last is a library book.)