1. While submitting your study permit application, did you mention you have a Co-Op, and did you attach proof of that?
2. Co-Op work permit, as far as I know, is a closed work permit. It will mention your school as your employer, to prevent students from using it as an open work permit and working 40 hours' full time. Under the conditions of the coop work permit, you can only work full time in the semester/period designated by your school.
Hope this helps you figure out what you got.