The class A shares are debt the common shares are ownership. The "Prefferred shares" represent shares that were issued as debt and will have stipulations like the 1/10 voting privilige and being able to convert to common shares etc.. The huge advantage to the class A shares is that they are less risky than the common shares and in the case of a chapter 11 the owners of prefferred shares get any money remaining in the company before the common share holders. Prefferred shares tend to get dividends/interest payments even when the common shares do not. Prefferred shares may have a time limit on there existance or when certain criteria are met they will be converted to common shares or be payed off.
Preferred Stock
Here is a link to a more indepth explantaion than I can go into right now. There are also some links on that page to articles on this subject and how it relates to common stock bonds among other things.