Thousands of foreign workers enter Canada every year to fulfill the labor market needs in the country. If you want to work in Canada, you probably need a work permit and there are different types of it.
Open Work Permit
It allows you to work on any occupation (that is not restricted) and for any employer.
Employer Specific Work Permit
This type of Work Permit allows you to work only for one particular employer.
Occupation Specific Work Permit
It allows you to work on only one occupation that is specified but for any employer.
Bridging Work Permit
You might have to apply for it if your work permit expired and you've applied for PR.