Every single registered domain has a minimum of two Name Server records which show where it's hosted i.e. by using these records you direct your domain to the servers of a certain hosting provider. In this way, you have got both your website and your emails handled by the very same service provider. On the lower level of the Domain Name System (DNS), however, there are a number of other records, such as A and MX. The former shows which server handles the site for a given domain and is always an IP address (18.104.22.168), while the second one shows which server deals with the emails and is always an alphanumeric string (mx1.domain.com). For instance, whenever you enter a domain address in your browser, your request is sent through the global DNS system to the company whose NS records the domain name uses and from there you could be directed to the servers of a different provider in case you have set an IP address of the latter as an A record for your domain name. Having different records for the website and the e-mails suggests that you may have your website and your emails with two different companies if you'd like.