The high speed cdrw is a diferent standard
backwards compatible with "normal" speed cdrw.
For a 4x-12x cdrw media:
A High speed drive can burn either at 4x or 12x.
A "normal" speed drive can't burn he disc at any speed.
For a 1x-4x cdrw media:
Either the high speed and the "normal" can burn the disc at 4x.
The same can be applied to Ultra High Speed media.