A Question About Maitland's ''Surrender of Napoleon''

Feb 2019
Earlier today I was looking through some of my books and searching for some info about them. One of these was Surrender of Napoleon by Frederick Lewis Maitland. This book was written in the 1820s and as such is long out of copyright, I got it from Gutenberg about 4 months back and I noticed this version has around 120 pages in the EPub format, this format has tendency to reduce or increase the actual page number depending on the size of text, so I can assume that the printed copy probably had a bit more pages. However once I looked for the book on Amazon and Google books there were some editions that roughly corresponded to this, displaying 120-160 pages, but then there were some that displayed the page number at a much larger 350-370. (For example: The Surrender of Napoleon and The Surrender of Napoleon ) Using the preview option from Amazon I noticed that the versions for both have exactly the same text in the beginning.

What is the difference between these editions? What are those extra ~250 pages about and is the one with 120 pages complete or cut short?