ABC News' David Chalian Reports: White House Chief of Staff Rahm Emanuel walked a bit of a tightrope this morning when comparing and contrasting the styles of President Obama and Mr. Emanuel's former boss in the White House, Bill Clinton. He appeared to make certain he said nothing to offend President Clinton while painting the challenges facing President Obama as far tougher than those inherited by the 42nd president."Obama has one of the most disciplined minds I have ever seen," Emanuel said at a breakfast roundtable with reporters sponsored by the Christian Science Monitor. President Clinton has an "unbelievably creative mind," he said in a side by side comparison of sorts.Mr. Emanuel sits in the rare position of having worked up close in the White House for both President Clinton and President Obama. A couple of weeks ago in the "Inside the Obama White House" special, NBC News' Brian Williams asked Mr. Emanuel to do some comparative analysis, but he demurred.Today, Emanuel mused aloud about the two Democratic presidents he served."The world that they are dealing with is fundamentally different," said Emanuel. "President Obama has what Clinton had by a quotient of 10," he added.No hard feelings to the sensitive Mr. Clinton, though. Mr. Emanuel said he loved working for Mr. Clinton and called him a "very significant president."He offered those kind words before launching into high praise for President Obama's speech to the Muslim world in Cairo earlier this month."I think that Cairo speech will go down as one of the most significant speeches given by a president," he said.He then conspicuously compared it to the speeches of Kennedy and Reagan. Not those of Bill Clinton.