Rick, this is from the Kodak website:
What is the difference between Type I, Type II, and Type III PC Cards?
Type I - First standard defined by PC Card Association. Dimensions: 85.6 mm x 54.0 mm x 3.3 mm.
Type II - Second standard form factor defined by PC Card Association. Dimensions: 85.6 mm x 54.0 mm x 5.0 mm. The KODAK Picture Card with Adapter fit into a Type II slot.
Type III - Third standard form factor defined by PC Card Association. Dimensions: 85.6 mm x 54.0 mm x 10.5 mm. An example of this is the PCMCIA hard drive in a KODAK PROFESSIONAL DCS Digital Camera.
One of the differences is physical size. A Type I card fits into a Type II slot. A Type I and Type II cards fit into a Type III slot. Due to the larger physical size, the Type III card does not fit into a Type II or Type I slot. Similarly, a Type II card does not fit into a Type I slot.
The ONLY difference between the card types is the size - and the fact that IBM Microdrives (for instance) are Type II cards. I have yet to see a regular CF card that
wasn't a Type I card.
For yet more info:
http://www.digital-camera-online.com/compactflash.htmlAnd for information on the card speed etc., see:
http://www.dpreview.com/articles/mediacompare/