Mulligan, are you talking about APC props? If so, you see the dia. + pitch of the pattern props? Pattern props generally have a lot of pitch to dia. (high pitch to dia. ratio) They are stronger to handle the powerful engines involved.( they have a different hub design, etc.) They're for a more specific application than general "sport" props, and sport props are less expensive. I'm sure there are more differences, but off the top of my head, I think these are most of them.