Is there a book or site that has a history of Smith & Wesson firearms? I'd like to learn more about the history of when what was manufactured and the difference between different models.
The book you're looking for is called the Standard Catalog of Smith and Wesson, sometimes abbreviated as SCSW, by Jim Supica and Richard Nahas. You can get it from Amazon and other places.
While the S&W Standard Catalog Third is a good reference - and is among my reference books - it's also inaccurate in various places and, because it was last published in 2003, lacks for information on others. Something even the authors admit within the book.
Therefore, I suggest getting as many references as possible. Just let your wallet be your guide.
It is still the best all-around reference book on S&W that is available at this time, and is a great place to begin. I have both the 2nd and 3rd editions.