<http://www.usb.org/info/usb_nomenclature>
Extremely abbreviated version:
The USB Hi-Speed logo indicates the device "...supports the Hi-Speed USB data transfer rate of 480 Mb/s..."
The USB logo is for "...products operating at Original USB speeds (1.5 Mb/s or 12 Mb/s )
The USB 2.0 standard includes both. This was to make 2.0 compatible with the older 1.1 devices. In other words, all other things being equal, your old device can be plugged into the faster USB connection on your newer computer.
A USB 2 label does NOT mean it's faster. Only compliant with with 2.0 spec, which means it could be the slow 1.1.
Only the USB Hi-Speed label means it's faster.
Lots more info on the web site.
See you later, gs <http://www.georgesphotos.net>

