There is no such an official ranking list for German colleges and universities and there is also no such differentiation between key universities and ordinary universities. Each university has its own specialty and is strong in a certain sense in its major arrangements. At present, some media evaluated the present statuses of the German colleges and universities and ranked them in terms of majors, teaching staff and the software and hardware.
For the detailed information please visit the following website: www.university-ranking.de.

This is probably a kind of subjective supposition or incorrectly relayed misunderstanding. The universities in the eastern part of Germany are also rather excellent. Many of such universities such as Humboldt University of Berlin (HU), Leipzig University (Universitaet Leipzig) and Dresden University of Technology (TU Dresden) are all famous around the world and numerous famous scientists and scholars were graduated there. We might say that the teaching and scientific research hardware in these universities were relatively poorer, however, this situation has been greatly improved in the last decade after the reunion of the Eastern Germany and the Western Germany. Some of the newly founded universities of applied sciences are comparatively late in development, but the teaching quality in these universities is also continuously improving.