I'm not sure what compression format they would have. I thought the file saved from Maple would be the same size. The one file I used turned out 30% larger but a file I just tested was only 7% larger -- still larger nonetheless.
If I Write("c:/test.jpg",testfile) then of course because the extension is jpg it will be smaller but saving extensions exactly the same produces different file sizes. I suppose not all programs save the same files exactly the same way.
However, reading and writing the same file sequentially through maple a few times doesn't change the file size, which does suggest the way the original file was saved is not done the same way Maple saves it.
So this brings up another question, does this mean that Maple does not save files in the most efficient way?