It’s the same software. Sony has done this because Movie Studio users seem reluctant to use the words “Movie Studio” when asking for help and say, “I Have Vegas Platinum 10” or “I have Vegas 10” when in fact “Vegas 10” means “Vegas Pro 10” to most people. This leads to them getting the wrong help because people think they have the Pro version and answer the question referring to features that Movie Studio doesn’t have. This leads to customer frustration and confusion.
Actually it became a kind of joke. Look at this box shot of Movie Studio 10 below. What are the BIGGEST words on that box? (and the smallest) People still said I have VEGAS and never called it MOVIE STUDIO!

So Sony finally took the word “Vegas” out of the title to once and for all eliminate the confusion. Movie Studio is not Vegas Pro… it’s Movie Studio. Call it what it is so people know what you are referring to.
~jr
http://www.johnrofrano.com
http://www.vasst.com