You're only seeing 'conflicting information' because you are clearly not bright enough to go to the most relevent source, the CBSA site.
Identification requirements for U. S. citizens and permanent residents
If you are a U.S. citizen or permanent resident, you must carry proof of citizenship such as a passport, birth certificate, a certificate of citizenship or naturalization, a U.S. Permanent Resident Card, or a Certificate of Indian Status along with photo identification. If you are a U.S. permanent resident, ensure you carry proof of your status such as a U.S. Permanent Resident Card.