Command Control engines are operated from a "walk-around" hand held remote and and have potential to electronically operate many features. But for many folks the key feature of command is ability to easily run more than one train in the same power district, block section or oval. You can for example double-head or run multiple engines linked together.
In Conventional you are normally operating by using transformer throttle handles to control engines while residing at one spot----a "Control Panel". But, Conventional can also be operated from a hand held remote by linking a Track Power Controller[TPC] or similar controller to the transformer.
However in Conventional, one cannot run multiple engines in the same power district without setting up a traditional "Cab Control System" of insulated track blocks. Many, such as myself run both in Command and Conventional controlling from the remote since we have both command and conventional[postwar, Thomas the Tank,etc,] engines that we favor.
Some might good advice in all the posts above--good luck and happy railroading!
