Contents May Settle During Shipping (or "Why Apple Updates are Different Sizes on Different Computers")

Updating a MacBook and a Mac Mini to 10.5.3.  One is downloading over 400MB, the other is about 198MB.  So I was obviously wondering why the difference.  Apple has an article about it.  Apparently the smaller one is just a patch, the larger is the full thing.  What's curious is that the MacBook has next to nothing on it, and the Mac Mini is loaded with stuff.  Seems to me that the Mini should have downloaded the large one, not the path, and the MacBook should have downloaded the patch.  So there you have it.