The answer to the question posed in the headline, that is the commonalities between the ObamaCare website and Canada's failed gun registry, is software company CGI. The Conservatives under Canadian PM Stephen Harper dumped the gun registry last year deeming it ineffective and too costly. The Firearms Registry had been plagued by cost overruns from day one.
Sun News has more on other failures by CGI with regard to healthcare related databases in their report below.
Breitbart has more on these failures by CGI.
The failed gun registry was only one of CGI's many Canadian failures, which included canceled contracts to build health care databases in the provinces of Ontario and New Brunswick. Despite CGI's checkered record, the Obama administration awarded its U.S. subsidiary, CGI Federal, the $93.7 million contract to build healthcare.gov, part of $678 million in health care services contracts awarded to the company.The Washington Post has more on how CGI Federal, a wholly owned subsidiary of Canada's CGI Group, went about winning the contract for the ObamaCare website. In a significant omission, the Washington Post fails to mention the role of CGI in the failed Firearms Registry.
It is obvious to me that no one in the Department of Health and Human Services did any sort of due diligence on CGI or CGI Federal. It could be just a coincidence that CGI was involved in a gun registration scheme and was the firm selected by the most anti-gun administration in recent memory to handle their healthcare exchanges website. I know correlation is not causation but one does have to wonder.