For a Danish teenager - existence of the term "community service" can result in suspicion of a criminal record.
Voluntary work exist on paper in Denmark but it is not done for free. Often employees will contribute some hours if the marketing department in their firm ask them to do voluntary work while being full compensated during work hours. Please notice that it is not about the single person giving aid to others. It is about to give an impression that the firm the volunteers work for take on social responsibility which can increase sale. As Danish employees are generally known to be faithful and dedicated in their jobs, most will go the extra mile to advertise their firm as social responsible.
However, Community service is used by Danish courts too and it is done in cases where degrading of the convicted is a part of the sentence. It is causing some problems considering that the European Court of Human right has ruled that a punishment must not be degrading which would be in violation with the Human Rights Convention (Tyrer v- the United Kingdom), but it is still practiced.
So Danish exchange students should ask into what the policy of the school district they will study in has. It is their entire future which is at stake.