Hi,
An apprenticeship (Ausbildung) usually takes 3-4 years. There are hybrid models (duale Ausbildung) where you still go to school while working in a company part-time.
An internship is shorter and has a different aim: you work for a company so that you can check if this profession is fitting for you and the employer can see on the other hand if you are the right person for that job. An internship might lead to a full-time job, but first of all it helps you to gather work experience.