You can see the difference that experience makes at http://www.youtube.com/watch?v=-lWXwWoWgYI
Michelle's is more nuanced, positive and empathetic, in a way that really connects with women voters and the middle class. She also has wonderful children with good values. When she speaks, she has a quiet dignity, and never comes off as whiny, or the "nosy neighbor" type. She's a proven consensus builder who doesn't need to bully or badger those she oversees.
Her leadership abilities were honed while serving on the staff of the mayor of Chicago, a city of three million people, where she helped implement programs that helped millions. This dwarfs Palin's responsibilities at Wasilla, where Palin left most of the day-to-day matters to a hired manager. In retrospect, Palin could've used Michelle's hands-on abilities to oversee legal and business matters, as she left Wasilla deep in debt.
To her credit , Palin does have a year of experience managing Alaska, which is about one-fifth the population of Chicago. (I'd like to tell you more about Alaska, but I couldn't find it on the map. I hear it's near Moscow, and, as such, is the basis for Palin's foriegn policy experience.) In comparison, Michelle Obama serves on the board of directors of the Chicago Council on Global Affairs and has traveled extensively outside the United States.
Michelle has better maverick credentials. She left a successful legal career to go into public service, and went on to work for the University of Chicago Hospitals as Vice President for Community and External Affairs. Admittedly, the hospitals only employ a third as many people as the State of Alaska... but the fact remains that Michelle Obama has Vice Presidential experience... and Sarah Palin has a speech.