What does mean two-side- or one-side-matching?

1. One-Side-Matching
The students choose there presences about courses. After the the voting-timeslot for students the matching can start.

2. Two-Side-Matching
The Students choose there presences about course.
After the the voting-timeslot for students the voting-timeslot for course-organizer starts.
The course-organizer choose there preferences for students.
After the voting-timeslot for course-organizer the maching can start.