There is a clear difference between the AStA and a student council at a university or college. The AStA, also known as the Allgemeiner Studierendenausschuss (General Student Committee), is the official representation of the students vis-à-vis the university and other institutions. The AStA is made up of elected representatives from all departments and thus represents the interests of all students.
The Fachschaft, on the other hand, is a group of students within a particular department who voluntarily join together to represent their interests. For example, the Fachschaft organizes tutorials, events and excursions for its members and assists them with questions or problems.
Although both the AStA and the Fachschaften aim to represent the interests of students, they differ in their structure and areas of responsibility. The AStA has broader responsibilities and represents all students at a university, while the student councils deal with specific issues within their department.
Overall, both the AStA and the student councils are important players in university life and help ensure that students' needs are heard. It is important to understand the role each plays and how best to use them to make your studies successful.