The Name Servers of a domain name show the DNS servers that manage its DNS records. The IP address of the web site (A record), the mail server that deals with the e-mails for a domain name (MX records), any text record in free form (TXT record), pointing (CNAME record) etc are extracted from the DNS servers of the website hosting company and for any domain address to be using them and to be directed to their hosting platform, it has to have their name servers, or NS records. If you want to open an Internet site, for example, and you type the URL, the browser connects to a DNS server, which keeps the NS records for the domain address and the request is then forwarded to the DNS servers of the hosting provider where the A record of the website is retrieved, allowing you to see the content from the proper location. Normally a domain has a couple of name servers that start with NS or DNS as a prefix and the contrast between the two is simply visual.