Can any one suggest me what is the major difference between XML & HTML Site Map ?

XML is a well formated site routing map, implemented as per XML protocol for Crawlers but HTML sitemap is a web document in which list of web pages listed as hyperlinks for site visitors to reach published web pages quickly. According to Search Engines, they quickly crawl XML sitemap and People quickly recognize what exactly inside in a website with HTML sitemap. However, Search Engines also consider HTML sitemap for indexing the web pages but they mostly prefer XML sitemap.