One of the most important thing between the two styles is the focus on honesty. The Realist authors wanted to express things as being exactly the way they were, without adding anything to over glorify. The Romanticism writers also had a strong focus on honesty in their writings, and wrote about the world and society exactly as they saw it. Crane does nothing to make the Civil War glorious in his novel The Red Badge of Courage, and in fact it must have taken an effort to write about such an average person as the protagonist of that book, who runs from the first battle he sees. Thoreau wrote in the essay Civil Disobedience about going to jail and how a person should not really need the government. These were very radical ideas, but because of his honesty he wrote about them anyway.
Another similarity between the Realist Stephen Crane and the Trancendentalist Emerson is that both had similar uses for nature in their writing. After the protagonist in The Red Badge of Courage runs from his first battle he goes to a forest, away from the society of other people to collect his thoughts (Crane). Emerson wrote about nature as the thing that keeps a person in touch with morality (Wayne). Both of these writers use nature as a place to go when serious thought and reflection.
Despite the really huge change between the Realist and Romanticism, the two styles really had a decent amount of things in common.
Crane, Stephen. "The Red Badge of Courage." By Stephen Crane. Search EText, Read Online, Study, Discuss. Web. 24 Feb. 2012.
Thoreau, Henry. "Thoreau's Civil Disobedience - 1." The Thoreau Reader. Web.
25 Jan. 2012. http://thoreau.eserver.org/civil1.html.
Wayne, Tiffany K. "Nature." Critical Companion to Ralph Waldo Emerson: A
Literary Reference to His Life and Work, Critical Companion. New York: Chelsea
House Publishing, 2010. Bloom's Literary Reference Online. Facts On File, Inc.
Web. 15 Feb. 2012.