Can anyone tell me the difference between these two brakes?

Thank you

I had both for a little while at a time, so if I can remember correctly...
HMX 2 appears the to be the pick, it's one piece, the fixed pad adjustment is a fairly crude design but won't freeze up like HMX 1, the pads are a different shape to regular hayes and I have no idea how much they cost. HMX 2 appears to be almost entirely metal, so maybe its a little heavier too but seems a little more robust. No idea on the technical specs that have changed, these are just my observations.

But if you're looking to buy cable discs then I wouldn't pick either of them over avids.

Thanks for that. I have had Avids and would like to use them again, but my new bike is coming with HMX-2's (Lithium 3), so thought if I would find out a little about them.