McCain's was moderates & independents, whereas Romney's was basically just middle- & upper-class Reagan conservatives & professionals in the suburbs.
Those were the groups that McCain and Romney targeted. But both failed.
In 2008, Obama won moderates 60-39%. (In comparison, Bush lost them by just 50-48%). Romney in 2012 didn’t win anything outside of the south and the Heartland, except Alaska? So I don’t think he won the Reagan Democrats and the professionals in the suburbs.
Romney did better in Orange , Tarrant , Cobb , Fairfax than McCain while he did worse than McCain in counties like Mahong, OH.
Romney did not do good in the industrial heartland at all and that was Obama’s firewall which kept Romney path to 270 extremely narrow
