Newspapers have an incredibly important social function as muckrackers, exposing corruption, explaining politics, and breaking news. Even the New York Times, which is as good of a newspaper as you'll find these days has 'native advertising' which is virtually indistinguishable from regular articles.
I'd argue that the distinguishing feature would be the 'Paid Post' banner that remains at the top of the article, even as the reader scrolls.
I know the writing style and content still resembles actual articles and it might be easy to miss this disclaimer if you're paying attention only to the content but it's only fair to mention that they do, in fact, label paid content as such.
They USED to do that. Now they're owned by conglomerates and billionaires to parrot their ideals.
[1] http://en.m.wikipedia.org/wiki/Propaganda_of_the_Spanish–Ame...