Yellow journalism
Both papers were accused of sensationalizing the news (making it seem much more important than it really was) in order to sell more newspapers, although they did serious reporting as well.  The New York Press used the term "Yellow Kid journalism" in early 1897 after a then-popular comic strip, to talk about the newspapers of Pulitzer and Hearst, which both published versions of it during a circulation war.  Ervin Wardman, publisher of the New York Herald (which was not "yellow journalism") invented it.