The Name Servers of a domain show the DNS servers that deal with its DNS records. The IP address of the web site (A record), the mail server that takes care of the emails for a domain address (MX records), any text record in free form (TXT record), directing (CNAME record) and so forth are obtained 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 needs to have their name servers, or NS records. If you want to open a website, for example, and you input the URL, the Internet browser connects to a DNS server, which keeps the NS records for the domain address and the request is then redirected to the DNS servers of the hosting provider where the A record of the website is obtained, allowing you to look at the content from the right location. Ordinarily a domain has a couple of name servers that start with NS or DNS as a prefix and the contrast between the two is only visual.