One of the main differences between DC and Marvel comics is that in the former, the good guys are loved by the masses while in the latter, very often the good guys are hated or at least viewed with suspicion. (Yes I've used the passive voice all over the place in that sentence.) When I was younger, I thought this a point in favor of Marvel, because its creators were sophisticated enough to realize that the public can be morons (just look at democracy).
However, after watching Superman Returns, I have to revisit that. I think the Superman movies very accurately depict the Man of Steel as a hero to the masses. (I don't want to spoil anything, but there's a great ending to the opening action sequence where Superman receives applause, and this is completely believable.)
What's the difference? I think at least two things: One, Superman doesn't wear a mask, whereas Spiderman does. Second, Superman can hang out with the masses if he wants; he doesn't need to run away quickly like Spiderman. This is because Superman (in contrast to just about all others) can choose to leave whenever he wants; even if the entire police force shows up to detain him, he can just fly away. In contrast, Spiderman has to skedaddle after foiling the bad guys, and so people can't be so sure of what happened.
(Granted, you can say DC is unrealistic because Superman really would need to wear a mask if he wanted to be Clark Kent.)