Why do I get inconsistent WHOIS record response?

Sometimes registrant information shows up under WhoisRecord and sometimes it shows up under WhoisRecord→registryData. For each domain name there are at most 2 WHOIS records, one from registry (eg. Verisign) and one for registrar (eg. GoDaddy). We return the registry WHOIS record under WhoisRecord→registryData and registar WHOIS record under WhoisRecord. For most TLDs other than com/net, only registry WHOIS record exists.