The RM is bigger. It's basically the same size as a DF, but with a penetrator tip and I like the handle better. I know all the choppers here like the Res-C, but the handle on the RM is beautiful.

If you'd like to see some RM pics to see how they compare, you can see mine here: Rat Mastiff and Swamp Rats

than whats the chopweiler? in between the rat mastiff and ratweiler?

The chopweiler is the same size as a RW, just shaped to be more of a chopper than a general use knife.