Mac App Store
The Mac App Store offers a wide range of games and apps from both Apple and third-party developers. It is also used to distribute new versions of OS X, security fixes, and firmware updates, along with updates to stock Apple apps like Safari. While developers have the option to offer apps through the Mac App Store, Mac apps can also be installed outside of the Mac App Store through traditional downloads.
Apps installed through the Mac App Store typically offer greater security as they have been vetted by Apple and are free from malicious code.