Roscoe... from the first link I posted for you:
The only difference between CF Type I and CF Type II cards is the card thickness. CF Type I is 3.3 mm thick and CF Type II cards are 5mm thick. A CF Type I card will operate in a CF Type I or CF Type II slot. A CF Type II card will only fit in a CF Type II slot. The electrical interfaces are identical. CompactFlash is available in both CF Type I and CF Type II cards, though predominantly in CF Type I cards. The Microdrive is a CF Type II card. Most CF I/O cards are CF Type I, but there are some CF Type II I/O cards
The difference in thickness is pretty obvious. Normally I'd measure it with a vernier, but you shouldn't have any problems with a Ruler! Type 11's came out to get more stuff in the cards. As long as the door opening is wide enough, or on a laptop there are 2 narrow (type 1) slots one above the other, but both flaps open together - there is enough headroom to fit in the thicker type 11 card. So I'd always buy a reader which can take the thicker type11 card, and Microdrive to be future proof. A 7HI can write a lot of big files so I'd definitely look further than 32Mb for media!