What is the difference between redirecting a domain and setting-up the Domain Name Server (DNS server)?

Redirecting a domain points traffic from a new domain to an existing domain, permitting continued use of the old domain to access a website. Visitors to your site will see the new URL change in the URL bar to the URL that it is directed to.

Setting up the DNS server makes the .realtor™ domain resolve to a hosted set of webpages as the default domain for that website.  This is a technical setting which requires a set of DNS server info. Visitors to your site will not see the URL change.