Forum Moderators: open
Seriously, the pages listed are those that Google has cached and can bring up in search results. The larger number is probably some kind of inaccurate guess at the number of pages it really knows about. Take the number of pages you actually see in the results as the true measure of how much of your site Google knows about.
Nothing? Umm, you did add the &num=100&filter=0 to the end of the long [google.com...] address in the browser address bar, didn't you?