Question: What is the difference between the CSV (Comma Separated Values) and XML export formats?
Answer: The CSV output format is simply a text file with each record from the crawl per line, with the columns separated by commas. This format is useful if you wish to import the contents of your sitemap (or a list of URLs from your site) into a spreadsheet application (such as Microsoft Excel) or a database.
The XML sitemap is a more complex file that conforms to the sitemap standard published on sitemaps.org. In addition to being written in an XML format, this sitemap optionally includes the date when the file was last modified, a relative priority value and an approximate change frequency.
Sitemap Creator does not currently support spanning multiple sitemap files.