If you have a Kodak camera, they use SD's (secure digital) or MMC (multimedia card). There are many different brands however...I don't personally care for Sandisk, but that's just me...I have Lexar's and Meritlines and have been pleased with both.
Compact Flash is a different kind of card altogether (flatter and larger). But they have come in many different brands as well but, like GrumpyBa*D said, they are typically smaller. They now have SD's that go to 2 gigs (but the larger the storage area, the more pics you will loose if the card crashes...I prefer either 128's or 256's - I also have a Kodak).
Hope this helps!