There's an excellent piece by Elisabeth Bumiller in The New York Times which makes the point that one area in which Bush and McCain now differ is foreign policy. Specifically, Bush has -- without explicitly admitting any errors -- moved away from his earlier, disastrous policies on a number of fronts.
McCain, by contrast, has stayed much closer to the true faith. Bumiller explains that "as the administration has taken a more pragmatic approach to foreign policy, the decision of Mr. McCain to adhere to his more hawkish positions illustrates the continuing influence of neoconservatives on his thinking even as they are losing clout within the administration." Of course it's relevant here to recall that McCain reached these positions first running as the neocon candidate in 1999-2000 while Bush tried to straddle the neocon-pragmatist divide. Now the two men have returned to form, with McCain promising a return to the sort of policymaking we saw from Bush in 2002-2005.