Discrepancy between iPhoto and its package contents

I am using OS X version 10.5.8 and iPhoto '09 version 8.1.2.

When I go into iPhoto Package Contents, some pictures that show up in my iPhoto do not show up in the Package Contents (neither the Original or Modified folders). I have done a search of 4 pictures in particular and could only find 1 of them in the package contents, even though all 4 of them show up in iPhoto.

And, oddly enough, the total number of pictures that iPhoto shows is 23,780, but when I total up the images within the Originals folder is 25,191.

So, some pictures seem to be missing from the package contents but for some reason, the package contents shows more pictures than iPhoto shows.

I thought the package contents was supposed to be exactly what was in iPhoto. Any idea what I am missing or what could be wrong?

(The reason I am even looking in package contents is because I am working on backing up all my pictures, but my external hard drive is not formatted for iPhoto since it is used by others that don't use Apple products so I was accessing package contents simply to copy the Originals folder to our external hard drive. I wasn't making any changes to the package contents).