What's the difference between having a sitemap.xml used through Google Webmaster Tools and creating my own sitemap.htm/sitemap.html ? I currently have both you see - the one on my website homepage links to sitemap.htm - the xml is just in my root directory and not linked anywhere on my website. Should there only be one or the other?
There are huge difference in having sitemap.htm or sitemap.html and sitemap.xml generally sitemap.htm is used for visitor if he/she dosen't able to find a web page which they are looking for. through sitemap.htm any users can able to find that web page which they are looking as sitemap.html contains all the links on your website having. Whether sitemap.xml having same terminology but its only for crawlers. i.e. if your sitemap.xml contains 100 link then crawlers can understand that site contains 100 web pages. its necessity of sitemap.xml One more thing its not necessity to give link to sitemap.xml but you can give it to sitemap.htm. Sitemap.htm and sitemap.xml both are needed for websites. Now i pretty much sure that you can get the difference.
you can find detailed information at blog.crownpointdesigns.com/2009/02/16/sitemaphtml-vs-sitemapxml/