Difference between the sitemap.xml and sitemap.xml.gz files?

Difference between the "sitemap.xml" and "sitemap.xml.gz" files?

The "sitemap.xml.gz" is a compressed version of the "sitemap.xml" file. It has the same content, but is significantly smaller than the other one. This helps you and the search engines to save a lot of traffic. Since all search engines support compressed sitemaps, you actually don't need the "sitemap.xml", but maybe you or your visitors want to view them from time to time so keeping it doesn't hurt.