For instance in The Sound and the Fury he spends several pages describing a white picket fence. Flannery O Connor writes much shorter and concentrates on the events of the plot much more than the physical descriptions of things. All she says is that the prostitute is fat and wearing pink underwear. She would have then talked about what was happening around the fence. This aspect of writing is just one difference in the two writers styles.
Some writers have styles that vary widely within themselves.
Jim Watson wrote a book called Double Helix. In this book he wrote from two very different perspectives. At some points in the book he wrote from the prospective of a scientist. He described the aspects of his work on the discovery of the structure of DNA from a very scientific standpoint. When he wrote about the events of his life outside of the lab he wrote from a much more narrative and reflective standpoint.