Domain privacy is a service offered by a number of domain name registrars. A user buys privacy from the company, who in turn replaces the user's info in the WHOIS with the info of a forwarding servic

The Internet Corporation for Assigned Names and Numbers (ICANN) broadly requires that the mailing address, phone number and e-mail address of those owning or administrating a domain name be made publicly available through the "WHOIS" directories. However, that policy enables spammers, direct marketers, identity thieves, or other attackers to use the directory for personal information about those people. Although ICANN has been exploring changing WHOIS to enable greater privacy, there is a lack of consensus among major stakeholders as to what type of change should be made.[9] However, with the offer of private registration from many registrars, some of the risk has been mitigated.

If you are not familiar with the term, whois privacy is a service offered by most domain name registrars that protects your information as a domain registrant from people performing a "whois" on your domains.

As you can see the one with whois privacy does not reveal the information about the registrant. Instead it displays the name and contact information of DomainsByProxy, which is one of the companies offering these privacy services (you also have WhoisGuard, WhoisProtect and so on).