Memory shown on Desktop Manager vs. Memory shown in My World

[schnorwg]

When I connect my blackberry 9530 to my computer the Application Loader says I have 40 MB of free space, but when I go to my listing of application in "My World" it says I only have 9 MB.  I only have about 10 apps, but I can't download any more because it says I don't have enough memory.  How can I make use of the 40 MB and why is what is shown in My World different?