How does Diamond explain the difference between the Paleolithic and the Neolithic in Guns,Germs, and Steel? How does Jared Diamond explain it?

In this book, Diamond never actually comes out and
explains the difference between the Paleolithic and the Neolithic in so many words.  He
does not say "these two eras were different because..."  Instead, much of the book is
dedicated to understanding the implications of a change from Paleolithic ways (hunting
and gathering) to Neolithic ways (farming).

The most
important distinction between the Paleolithic and the Neolithic is that the Neolithic is
the time during which agriculture was discovered and developed.  Diamond describes the
differences that this causes at great length in many parts of the book.  Basically, he
says that the discovery of agriculture led to more developed societies with higher
population densities.  This, in turn, led to some societies developing "guns, germs, and
steel" while other societies did not.

The difference
between these two eras, then, is that the Neolithic had agriculture while the
Paleolithic did not.  Diamond says much of later world history revolves around which
areas experienced the change to the Neolithic first.