Kindly tell me that what is the difference between Black Hat SEO and White Hat SEO.

White hat SEO is ethical SEO. It's SEO techniques that search engines accept. White hat SEO techniques are beneficial for site visitors as well as for search engines.
Black hat SEO is the use of techniques that are unacceptable to search engines to boost a page's position in search results.

White Hat SEO is approved by search engines while Black Hat SEO uses techniques such as keyword bulking and spandexing which are frowned upon.