This is reflected in their attitudes about military action in Iraq. Clinton was for it in 2002 and was against it by 2007. Obama was always against what he called a "dumb war."
As for President George W. Bush's surge strategy, Clinton told Obama, in front of a surprised and dismayed Robert Gates, that her opposition to the surge was "political because she was facing him in the Iowa primary." Obama, according to Gates, merely conceded that opposition to the surge -- by whom? -- was political.
So perhaps it was not too surprising that Clinton told the Atlantic's Jeffrey Goldberg that "Hamas initiated this conflict" with Israel (a contrast with Obama's condemnation of violence on both sides), that Iran has no "right to enrichment" (which Obama is conceding in negotiations) and that Obama's refusal to aid acceptable Syrian rebels in 2011 "left a big vacuum, which the jihadists have now filled."
Clinton's dismissal of Obama's foreign policy philosophy was contemptuous. "Great nations need organizing principles, and 'don't do stupid stuff' is not an organizing principle."
Circumstances have changed, so the once-loyal secretary of state, now contemplating her second presidential candidacy, was engaging in Clintonian triangulation. She would be less rough than Bush, less dreamy than Obama: a Goldilocks candidate.
But perhaps circumstances have not changed so much. After Obama adviser David Axelrod tweeted that "stupid stuff" referred to the Iraq war, Clinton announced she was ready to hug the president again. There are lots of left-wing peacenik voters in Democratic primaries. You have to win the nomination before getting to the general election.
Clinton's turnaround was not as surprising, however, as Obama's. The president who declared in June 2011 that "the tide of war is receding" and that the long wars in Iraq and Afghanistan "will come to a responsible end" has ordered hundreds of U.S. troops back to Iraq and launched air strikes with no end in sight there.
For a politician whose range of acceptable positions has previously been very narrow, this is an astonishing turnaround. There is only one explanation: Obama's foreign policy is in shambles.