There are two types of work permits, open and closed. With an open work permit, you can work for any employer without any paperwork. You can even work for more than one employer at the same time.
With a closed work permit, you can only work for the employer listed on the work permit and more precisely in the position and the location specified in the work permit.
IEC working holiday is completely open but there are other IEC visas like young professionals that are tied to an employer.
