Downloaded iOS 7 to my iPad 3. Some differences exist between what is on my machine and on the fourth generation version, not to mention what is on an iPhone. The biggest difference with a fourth gen is the absence of airplay and airdrop. Problem is, there is no list of features and product comparisons. Also, Facetime audio does not work on my third gen. The option is there bbut I always get a "Facetime audio failed!" message when I try. Is there a list of system apps and improvements anywhere? How does anyone recognize a bug in the software?