The Apple Support Communities are an international user to user technical support forum. As a man from Mexico, Spanish is my native tongue. I do not speak English very well, however, I do write in English with the aid of the Mac OS X spelling and grammar checks. I also live in a culture perhaps very very different from your own. When offering advice in the ASC, my comments are not meant to be anything more than helpful and certainly not to be taken as insults.
OS X updates are usually released through Software Update in the Apple menu. The current process is that SU will then check with the Mac App Store to download the update. What is downloaded from the MAS is a delta update that adds the changes for 10.8.1 to your installation of 10.8.
If you see an update to Mt Lion in the MAS Updates pane, thet is the full My Lion installer app (4+ GB to download).The MAS is letting you know that the installer is available should you need to download it, perhaps for another Mac that you may own and wish to upgrade to Mt Lion. You can ignore this flag on the MAS if you do not need it.