“Work permit” is not an official term and there is no separate document for this. The official term is permission to commence gainful employment. This permission is granted by the Immigration Office by means of a note in the residence permit. Individuals from third countries require this permission in order to be allowed to work in Germany. This means that individuals from third countries are only permitted to work in Germany if they have a note relating to this in the residence permit.
EU and the EEA citizens require no residence permit to be able to work in Germany. Swiss citizens require only the Swiss residency permit.
Check your options using the Quick Check from Make it in Germany. Find out here whether you can live and work in Germany.