Mark Kleiman is busy making an idiot of himself in public trying to convince the blogosphere that Obama is offering something different and new in foreign policy compared to Hillary Clinton. Kevin Drum points out that he can't really discern any difference, and that, to be kind, Kleiman is projecting. Anyone who reads Kleiman's blog knows he has a deep, visceral hatred of the Clintons and will basically grab at (or invent) any straw to support his position. Supporting a good candidate (Obama) does not make his attacks on Hillary any less incoherent. It is going to be amusing (or appalling) to watch what he does next year when she is the Democratic nominee.
Even so, I think there is a difference between Hillary and Barack on foreign policy, and it is not in the substance of their positions. It is in the audience they are addressing. Targeting your audience is very important in my line of work (Web development) because you can't communicate effectively if you don't know who you are talking to.
In her foreign policy statements, Hillary is addressing the international community and other heads of state. She already speaks like the president. Foreign policy is aimed at the actors within that realm, and is done with diplomacy. She is looking at the long term needs of the nation to repair and restore normal relations after the BushCo disater. I'm not sure she cares if this plays well in Peoria - or Yearly Kos.
In his policy statements, Barack is addressing potential voters. He speaks like a candidate. It is rhetoric intended to gain votes, and does not give much attention to the long term needs. He has calculated that extreme statements now, which raise the ire of other countries, are necessary to secure domestic support, and can be moderated afterwards. It is campaign strategy, not foreign policy. His actual policy, as far as I can suss out, is nearly identical to Hillary's. Please note that nothing I've said here is meant as a criticism. I don't think he can afford to address any other audience at the moment.
What Barack reminds me of at the moment is nothing so much as Bill Clinton in 1992, saying things to please the voters and create a point of distinction between himself and other candidates. Remember Bill's pronouncements about China vs. what actually happened? If Barack is elected (which is an outcome I'm happy with, no matter my criticisms of his campaign), he, too, will walk back his rhetoric. For example, the nuclear option is back on the table simply because it is *always* on the table where the US is concerned.
In short, what we are seeing is the difference between someone who has been immersed in foreign relations for years and someone who has not. Their basic stances are the same, both are obvious improvements over the current Republican insanity, and the people they would call on to run the State Department would probably overlap. Hillary is a stronger candidate than Barack in this area because she has more exposure to foreign policy from a presidential perspective. Only the Big Dog himself and Al Gore can claim more.