CNET explains that Macintosh OS X Mountain Lion was a minor upgrade to the Lion operating system. It improved applications and provided useful new features for file sharing and social connectivity. Apple computer’s Mountain Lion was the ninth major operating system released for Macintosh computers.
Mac OS X Lion, released in 2011, was a substantial upgrade to the previous operating system. It featured several interface enhancements and upgrades to all the core applications. The Lion OS received numerous positive reviews and was the first operating system available for download through the Internet. Mountain Lion, released in 2012, received positive reviews, but it did not garner the same praise from critics as the previous upgrade.
As of 2014, there have been two additional Mac OS updates, including OS X Mavericks and OS X Yosemite. Mavericks was the first operating system upgrade released free of charge and available for download from the Apple store. According to CNET, this was the biggest upgrade since Lion, offering many improved features and better performance.
In addition to Mavericks and Yosemite, both the Lion and Mountain Lion operating systems are available on the Apple website for the convenience of users who cannot run the newer operating systems on older computer models.