Although you said this about Newt, this is how I view Romney.
Romney is a member of the wealthy 'elite' establishment that pats each others' backs and lines each others' pockets. Gingrich is a member of the Washington political establishment that lines each others' pockets while screwing America.
Romney wants to become president to fulfill his father's dream, and doesn't particularly care about what policies he may or may not support at any particular time. Gingrich want to become president to fulfill his own ego and will argue forcefully for whatever happens to pass through his mind at any particular time.
So you see, there's a difference.