According to the dictionary, 運転手 means driver and 車掌 means conductor. So, 運転手 would be any person at the controls/steering wheel of any vehicle, while 車掌 would be someone who "is in charge of a train and travels with it, but does not drive it" (according to an English dictionary. I am not an English native speaker so I can't grasp the difference between both words in English either). So, the latter is only for trains? and if he does not drive, what does a 車掌 do in a train?
If you could provide some example sentences that illustrate the difference between both words, it would be nice.