RCMP or any other police check is for criminality check and there is another background check (also called security check)
RCMP: criminal background, which can be more robust than just the name-record criminal history check, which probably means it can involve queries beyond arrest and disposition records, such as into whether any law enforcement body is conducting an investigation or the individual is a suspect or has known connections to those known to be involved in criminality (the name-record criminal history check is done periodically throughout the process, and is similar to one often conducted during any secondary examination at a POE, and it is mostly a query run against an arrest and dispositions database based on individual's name and date-of-birth)
CSIS: security background (while obviously the scope of this is not public information, it is readily recognized that it at least involves queries into intelligence sourced databases, and other government security databases, which might reveal activity or ties related to organized crime, terrorist organizations, suspect military history)
