Hello there: Fixed hubs - Mostly all fixed hubs are the same. There is no real difference in any of them apart from strength etc. A fixed hub works in the way that there is just a hub at the rear with a screw on cog fitted to it. So the cog at the rear is locked (Doesn't move). There for needing a freewheel at the front. That is where all your engagement comes from etc. Free hubs - In my opinion all free hubs are completely different. The reason being is that all your engagement is built in to the hub it's self. For example: A profile mini cassette Hub has 48 engagement points, which is a very nice amount of engagement to have. (I can't tell the difference between 72 engagement points and 48 engagement points to be honest with you. This hub is outstanding for trials on a mod. Super strong. Very reliable. Where as the Deng free hubs. Them again have 48 engagement points but people have had no end of trouble with them. By which i mean, hub shells cracking, hub generally exploding. Me personally would not recommend this hub. Are you seeing my point ? Not all free hubs are the same unlike fixed hubs. But to finish all that off. Free hubs gets my vote. A lot stronger and alot more reliable. Dan.........................................................