I think the thing that's different between Sanders and Obama (and the thing that makes me actually excited about Sanders) is that Sanders is talking about getting the people actively involved to achieve his goals. Simply put, he recognizes that he will accomplish nothing without the help of the people, which makes me think he will actively try to attain the help of the people. If he actively tries to get people involved in politics (telling people to write to their representatives or get involved in some other way) then I really think he can do a much better job as President because he'll have the influence he needs to accomplish the things this country needs. Edit -- To develop this a bit, I don't remember Obama being that big into getting the people involved. Perhaps I'm remembering incorrectly...
Obama marketed very well, the "Yes, We Can" posters were all over the place and the youth were involved in getting votes for him. I do remember people getting involved in the first election, the second election, most people just didn't care. I have not seen anything from Sanders that tells me differently. Nobody in my family knows who he is or what he've done so far.