Mountain Lion install size

Hi all,

I have recently bought the rMBP and installed a fresh copy of ML on it. I also installed a fresh copy of ML on my last year MBP. After finishing the installation, ML seems to take around 24 GB of space on rMBP and around 12 GB on my MBP. Though I know that retina display doubles the graphics size but the whole installations of the same OS can't be twice as large on rMBP comapred to the normal MBP. These figures do not include the iPhoto, iMovie, and GarageBand applications, just the OS X installation. However, the strange thing is the following; after the installation when I check the Macintosh HD and measure the sizes of Application, System, Users, and Library Folders, it adds up to only around 12 GB on rMBP and around 8 GB on MBP. I don't know where all the other HD space has gone? I know there is an internet recovery partition, but that doesn't take more than 2 GB on each machine. Can anyone explain why is it so and how can I receover this space on my HD?

Tissot11