iPhoto Library Sizes Different?

[asherman13]

In the process of slimming down my 80GB HDD for Leopard...

I discovered that iPhoto reports that my iPhoto Library is holding 9.1GB of photos, while the actual iPhoto Library folder in my ~/Pictures folder is sized at 11.06GB. Is there any reason in particular for the discrepancy, and is there a way to get rid of those 2 extra GB?

BTW I'm on a 1.83Ghz Core Duo MacBook Pro running Mac OS X 10.4.10 and iLife '08 (iPhoto version 7.1).

Thanks very much!