The Difference is a Charles Willeford crime novel wearing a cowboy hat instead of a fedora, riding on a horse instead of in a Plymouth, and set in the Sonoran desert rather than San Francisco or Los Angeles.
Johnny Shaw, the first-person narrator, is as unscrupulous as the hero of Willeford's The Woman Chaser or, for that matter Thompson's The Killer Inside Me or Williams's The Hot Spot. Shaw has a noble quest---to regain control of the land left to him by his father---but, as he pursues it, he takes whatever he needs and kills whoever is in his way.
It was normal for "paperback writers" of the 1950s and 1960s to write more than one genre: crime, western, sci-fi, or romance. In this book, Willeford seems to know horsemanship and the Sonoran desert as well as he knows the used-car business and Los Angeles in The Woman Chaser. I'm not sure this will make me a fan of westerns, but I enjoyed this one.