The way I understand duty descriptions:
1211: http://www5.hrsdc.gc.ca/NOC/English/NOC/2011/QuickSearch.aspx?val65=1211
supervisor: training people, managing work schedules, making sure things run smoothly - minor stuff like requesting supplies, sometimes doing the same job people he supervises do
- this is the person directly above lowest level employees making sure they do their job right and evaluating their performance
1221: http://www5.hrsdc.gc.ca/NOC/English/NOC/2011/QuickSearch.aspx?val65=1221
officer: higher up the food chain than supervisor, makes of helps make policies handed down to supervisors, approving / ordering supplies requested by supervisors etc
- this is the person directly above 1211 telling 1211 knows what does it mean the job is done right (policies), they get what they need to get the job done and reporting on multiple supervisors to the higher ups