President Bush and Vice President Dick Cheney have been unusually talkative in recent weeks, sharing candid thoughts in a string of exit interviews. But after eight years of a tight partnership that gave Mr. Cheney powerful influence inside the White House, the two are sounding strikingly different notes as they leave office, especially on one of the most fundamental issues of their tenure: their aggressive response to the Sept. 11 terrorist attacks. Mr. Bush defends his decisions as necessary to keep the nation safe, yet sounds reflective, even chastened. He has expressed regrets about not achieving an overhaul of immigration laws and not changing the partisan tone in Washington. And the man who got tangled up in a question about whether he had made any mistakes " he could not come up with one in 2004 " recently told ABC News that he was "unprepared for war," and that "the biggest regret of all the presidency has to have been the intelligence failure in Iraq." Mr. Cheney, by contrast, is unbowed, defiant to the end. He called the Supreme Court "wrong" for overturning Bush policies on detainees at Guantnamo Bay; criticized his successor, Vice President-elect Joseph R. Biden Jr.; and defended the harsh interrogation technique called waterboarding, considered by many legal authorities to be torture. "I feel very good about what we did," the vice president told The Washington Times, adding, "If I was faced with those circumstances again, I'd do exactly the same thing." The difference in tone, friends and advisers say, reflects a split over Mr. Bush's second-term foreign policy, which Mr. Cheney resisted as too dovish. It also reveals their divergent approaches to post-White House life. Mr. Bush, who is planning a public policy center in Dallas, is trying to shape his legacy by offering historians a glimpse of his thinking, while Mr. Cheney, primarily concerned about the terrorist threat, is setting the stage for a role as a standard-bearer for conservatives on national security. "The president's interviews are about creating a basis for historians to evaluate the context of his decisions differently, with more input from him," said Wayne Berman, who has advised Mr. Bush and is a longtime friend of Mr. Cheney. "Cheney is living in the moment of, 'There's a serious ongoing threat,' and I believe he sees himself more in a Churchill-like role, as the sentinel issuing the call for vigilance." Mr. Bush and Mr. Cheney still have lunch together once a week, administration officials say, and the vice president remains the president's staunchest defender. But while Mr. Cheney has been "loyal to a fault," said John R. Bolton, the former ambassador to the United Nations whose views often reflect those of the vice president, he is also "increasingly in a beleaguered position." In the first term, Mr. Cheney, backed by his close ally, Donald H. Rumsfeld, who was then the defense secretary, was ascendant, and his views about the aggressive use of executive authority and military might held great sway. But after Mr. Bush fired Mr. Rumsfeld in 2006 " the only presidential decision Mr. Cheney has publicly disagreed with " the vice president took a back seat to Secretary of State Condoleezza Rice, who pushed the president to pursue greater diplomacy with two countries he once called "rogue nations," Iran and North Korea. "Our ability to explain what we've been doing in the national security field for eight years has been wholly inadequate," Mr. Bolton said, "and part of that is because too many high officials in the administration were embarrassed by the decisions. Cheney has never been embarrassed by it, and now, in the last months, he is freer to make the kind of forceful and emphatic case for it that others were unwilling to make." Mr. Bush and Mr. Cheney appear to be giving more interviews than their recent predecessors. Dan Quayle, the last vice president not to seek the presidency while in office, gave three exit interviews; Mr. Cheney has so far given four. President Ronald Reagan gave five interviews during his last two months in office; President Bill Clinton gave seven. Mr. Bush has already given 10, to outlets as varied as Real Clear Politics, the Pentagon Channel, an Arabic television channel and a sportswriter for The Washington Post; the White House says more are to come. Historians say presidents, especially those who serve two terms, often grow reflective at the end of their tenure. "They tend to be exhausted, they're worn out, they're trying to make some sense of their administrations, and there's a natural tendency for them to want to give their own perspective," said Jay Winik, who got to know Mr. Bush and Mr. Cheney after they read his book, "April 1865," an account of the last month of the Civil War. Never the introspective type, Mr. Bush has been freely answering "how do you feel" queries, which he once routinely dismissed as "goo-goo questions," said his first press secretary, Ari Fleischer. He has also used his interviews to reveal his softer side. He has spoken of "my relationship with the Good Lord," joked about his wife's cooking and spotlighted social programs he regards as achievements, like education reform and his global plan to fight AIDS. If he has criticisms of President-elect Barack Obama, Mr. Bush has not shared them; rather, he has hewed to the Bush family credo of graciousness in departure or defeat. ("I think he's discovered his inner Bush," Mr. Berman, the adviser, said.) He also opened the door to a possible role for himself in the Obama presidency, citing his own decision to ask his father, the first President Bush, and Mr. Clinton to spearhead a fund-raising effort for tsunami victims. "President-elect Obama, I am confident, will call upon presidents to take on a mission," Mr. Bush told C-Span. "I will be happy to do it, particularly if I agree with the mission." Mr. Cheney has been less diplomatic. Like Mr. Bush, he has praised Mr. Obama for keeping Robert M. Gates as defense secretary. But on "Fox News Sunday" this week, Mr. Cheney shot back at Mr. Biden for calling him "the most dangerous vice president in history." And asked by The Washington Times for his advice for Mr. Obama, Mr. Cheney talked of the importance of personnel decisions, then volunteered, "Senator Clinton as secretary of state " I would never pick her to be my secretary of state." Both men say they look forward to private life. For Mr. Cheney, who has served in four Republican administrations, transitions are nothing new. "It's not my first time at the rodeo," he told The Washington Times. Mr. Bush, who became Texas governor 14 years ago, told ABC News that he was eager to "live life without the limelight." Yet both will have more to say. Mr. Cheney is likely to write a book. Mr. Bush is contemplating a farewell address, and says he will definitely write a book, to give Americans, as he told The Washington Times, "one man's point of view that happened to be in the center of it all."