difference between Lionel Mallet and mth alleghenny

MTH is in scale miles per hour. Lionel uses speed steps, which are largely meaningless numbers set around a non-linear scale. Somewhere in the legacy manual, it does give approximations. I think 40 smph is speed step 100 or so.

I run both mth and Lionel articulated engines. I find the speed control is better with the mth and it is easier to keep on the track. The sound intensity is louder with the lionel but the cab chatter is better by far with the mth.  The railking articulated engines are fun in that they will run on 0-31.  You don't have any problems with it de-railing as you do the engines that required 0-72.  I also run some Right-of-Way articulated engine which also run on o-31 curves. These engines have run very well and smooth. They have their oun special running character.