Although your created a short post, you have actually raised a very good and interesting question.
Although I'm not too sure on what the difference between the two is, I did find this video from Matt Cutts explaining the basic difference and which one you should go with if you only had one choice.
HTML site map is mainly for the for ease of navigation , they are easy to undesrtand..they are mainly for the human and not for the search engine..the problem with the HTML site map they are not able to updated by itself..
XML sitemap are for the search engine ..they are not understandable for a normal internet user..but they are automatic up datable ..you can set frequency over there...
Hello My advice ...Actually there is no difference. They help website visitors navigate your website or help search engines crawl your sitemap better. All in all, sitemaps are really important for search engines, site visitors and SEOER....
HTML sitemap is one of the most important tactics you can use to distribute your link juice efficiently within your site. XML sitemaps are useful if you are having crawling or indexation problems on your site.
HTML sitemap is for user point of view which shows the proper navigation structure of site. It means that a user can visit your sitemap and can easily find your pages.
XML sitemap is for search engine point of view and help the crawler to crawl your site.
HTML site map is mainly for the for ease of navigation , they are easy to undesrtand..they are mainly for the human and not for the search engine..
XML sitemap are for the search engine they are not understandable for a normal internet user but they are automatic up datable you can set frequency over there.