Background Verification is mostly criminality check within Canada. This would include criminality name checks with police (RCMP) records to ensure you haven't been arrested or involved in proceedings of a crime. If your name is very common or name and date of birth match other known criminals, you will be asked to provide a Finger Print to rule out your criminality.
Prohibitions include the overall eligibility requirements that prevents you from becoming a citizen. This would include your tax filing records, security checks from CSIS to make sure you are not part of a misfit organisation or organised crime connection or terrorism connection or a threat to Canada, foreign PCC validation and equating any of the foreign offences to Canadian criminal code to see if you are still eligible.