What type of work can I do and for what employer can I work?
Your decision letter from UDI states what type of work you can do and, if relevant, the employer you will be working for.
If you start working for a new employer but work in the same type of position, you do not need to apply for a new residence permit.
If you are going to start a new type of position, you must apply for a new residence permit, regardless of whether it is with the same employer or a new employer. You cannot start working in a new kind of position until you receive a new residence permit.