There is a slight difference between the two. Extracurricular activities are defined as the activities pursued formally apart from your academic activities. For example, you can participate in drama, debates and sports along with your formal education. On the other hand, hobbies are activities that you are passionate about and you can do anything to take part in them. In simple teams, the difference between the two is the level of passion involved.
Hobbies can be done in school or out, but extracurricular is talking about outside school. Extracurricular is used only when someone is in school, or comparing something to school which is why it's seldom used on resumes etc. If you have to choose between the two, choose hobbies